You could say that, in around 50 years, Portugal has undergone a radical social-geographic transformation, from relatively broad rurality to vast suburbanity. This is a process with the apparent contours of ineluctability , by which Greater Lisbon (the country’s bulging, macrocephalous ‘cranium’) has been transformed most radically.
First, there is the continual flux from rural areas to city outskirts, driven by changing economic forces, and pressing needs and aspirations. Along with a ‘first’ wave of legal immigration, arising from the colonies, summoned to counter economic emigration and the departure of military contingents to the wars that dawned across Portuguese Africa, from Angola to Guinea-Bissau.
Then, the sudden ‘return’, after 1974 (growing families subjoined), of many of those who had once departed to settle in the colonies, and many there born and raised and therefore ‘turning’ but not returning.
Then still, there is a diluted, but uninterrupted, wave of displaced return, of those who settle around Lisbon, having emigrated from rural areas.
Finally, several waves of immigration start to arrive, around the late 70s, from the new nations that had before delineated the Portuguese empire, and more recently from Brazil, Eastern Europe and Asia.
This is the rich social mix of Lisbon’s suburbs, to which we could add a steady leakage of city denizens, driven out by rising property prices and speculation, and the ‘tertiarisation’ of Lisbon proper (and also by a particular desire for the ‘garden city’, the gated suburb or a timid and superficial ‘rurality’).
It is not that this transformation could be perceived as a simple change from rurality to suburbanity: after all, many of those now taking up a cell in the suburban matrix would not have arrived from a rural setting, and Portugal's population would have grown.
It is more that the combined result of migratory fluxes from within Portugal and further afield, as well as outwardly, along with the population expansions and contractions associated with these, has led both to a relative desertification of the rural landscape and the rise and rapid growth of an accretion ring around - and in certain areas, inside - Lisbon proper.
Complicating this is suburban inflation’s indifference to administrative demarcations, and the shifting of social plates caused by in and out-flowing propensities: parts of Lisbon once the outer (rural or semi-rural) regions of a smaller city are now inner-city dormitories and social housing 'townships', sections previously semi-vacant have now been filled with stereotypically suburban ‘gated-concrete-and-brick-with-a-pool’ for a certain middle-class and the luxury markets, and a watered down version of the garden city has also monopolised parts of the outer belt. (Conversely, a few ageing and depopulated inner neighbourhoods are repopulated and regenerated by the permeation of some of this immigration into the city as far as its centre.)
In addition to this, ring roads, inner-city through-ways, parking lots, tunnels, and shopping mall nodes have warranted that the city remains perpetually partitioned, and a suburban expansion that flows inwardly as much as outwardly becomes hardy and lasting. Inadvertently or not, with this grid, it is large parts of the city that get compartmented along marked socio-economical lines, and entire sections that get ghettoised. If architecture and planning (or the absence of one and the other) produce segmentation, it is the suburban mode centred around the fast individual crossing of the city and its satellites and the city-suburb 'pendulousness' (the daily cycle of filling and emptying by way of the car) that causes the suburban slippage and mismatching that is bound, in turns, by acceleration or deceleration vis-à-vis a more paced temporality that we would infer as urban. The network of 'conduits' and 'nodes' that compartment in the name of a cavalcade towards the city and a concentration, of the reversal of an outflow, of a (hyper) fluidity that frequently grounds to a halt, of a circulation under or above, generate this phased temporality that oscillates between the 'plus' of a traffic that moves too fast (supra-urban) and the 'minus' of one (infra-urban) which flows too slowly. A traffic which, indifferently, organises itself with disregard for a certain urban etiquette, and groups and applies itself by the emplacement , anterior or concurrent, of a prosthetics (the unlevelling, the barrier, the fence, the drainage, the levelling, the tunnel, the flyover), so that the fluidity of smooth and uninterrupted tarmac may be produced - it is a whole membranous feat of engineering, whose end purpose is the production of a liquidity internal to the network, at the expense of imbalances, mismatches, halts and avoidances turned to the outside. At the limits of this fabric, in the grid of motorways and circulars laid across sections of the urban-suburban conglomerate, a weave of interdiction is created (as a deeper moulding) which forbids anything that is not the exact expression of the automotive paradigm above a certain plateau; to the point of excluding a large proportion of that same principle: the motorway, more than a conduit and a space of liquidity, is a place of prohibition and division close to autocracy; in the suppression without restrictions of everything beneath a certain level of automotive articulation, and in the imposition of an irreversible and virtually impassable dividing line (or one that can only be crossed at predetermined points). In any case, the automotive paradigm is, by nature, opposed to urbanity: it is not by chance that this same grid that allows and promotes fluidity is constructed, around or in rupture of the city, as a space of control, even when the city would have been shaped, to a great extent, by the car, and without it cannot now function. It is important to note, also, that these great suburban 'impressions' (the motorways, circulars, intersections and 'knots') that extend (or distend) the internal arteries that carve the city are, most of the time themselves, a product decreed and commissioned from within the city, in the urban State departments whose modality is, itself, phased between the urban and the national, often refuting the suburban interests caught between one and the other. 
It is a whole network of deep mouldings ( and of spaces on top of these modulated) that is created, whose patterns are those of mismatching, of slippage, of discord and, principally, of unlevelling and relevelling, and of circumscription. There is, certainly, an auto-tropism in the pursuing of the car and its service, in the fattening of the roads that then overfill, leading to their cyclical enlargement, to the point where, often, the surrounding space is lost: case in point, the great Lisbon arteries given over and transmuted by the car. 
Just over half a million live within city boundaries, but a third of continental Portugal’s population now settles in a large urban and suburban canvas spreading north and south of the river, with the Lisbon and Tagus Valley region recently topping 3.6 million.
Construction, and the relatively anarchic (and often poor-quality and speculative) building of high-density housing, has safeguarded that this process be met by rising numbers of new dwellings, often arranged in clusters or 'nettings' around and along major interlinking arteries – Portugal suffers from a shortage of quality housing, but not from a deficit of new homes.
Alongside this, lack of planning, soft regulatory systems and the often absent or deeply tolerant implementation of said regulations, has led to the mushrooming informal and self-built villages that now pepper the alcoves of Greater Lisbon.
This is the ticking pulse of the suburban mode and the suburban conglomeration: the commuter and semi-rural municipalities (the two often coalescing); the mixing of old and new; the high-density suppression of rurality, but also its resurgence in the “hortas” that dot every terrain vague; the roadside stands, restaurants and businesses; the relative absence of consolidation and public spaces, but also the persistence of the vast fields that frame most densely compacted suburbs; the unresolved spaces; the self-styled houses; the high-tech lumps; the hypermarkets, Ikeas and shopping malls; the surprising sophistication that can be found where least expected; the dilapidation of rural property; the (small) waste and obsolescence businesses and industries; the settling communities often taking abode matters into their hands; the consolidation of town centres and the attending growth in civic pride; the motorways, flyovers and intersections; the rejuvenation and reinvention of some of these spaces and places; the gated villages and condominiums; the ubiquitous car, but also the intermittent train, tram, metro and bus; the recent housing arranged in lines or clusters, but rarely in ‘city blocks’ of dwellings and commerce; the social division that grows hand-in-hand with suburban inflation and the split between centre and outskirts, but also the many suburban modalities that include the 'gated paradise', the informal settlement, the high-density dormitory (where dwellings and families are heaped), the centrality of the shopping complex, the brownfield, the conciliation of all the vital industries that the city cannot accommodate; the moulding and modulation of the reinforced concrete and tarmac of the great structural works; the density of the blocks that almost rest on each other; the rhizomic spaces; a certain hesitation and hybridisation; the unlevelling as the great paradigm of suppression and occlusion; high-density as a suburban mode adjusted to low wages; a whole industry of service to the the city of services.
It is a complex blend that may look decidedly disorderly - and from time to time deeply regimented - and in turns bleak. But it is also germinal and in many places the upshot of a State long demi-receding from the provision of new homes; and the sufficient planning, governance and regulation of the new towns that have inevitably sprouted around Lisbon. It is, in addition or subtraction to all this, a chain of places where, here and there, the surrealism inscribed in topological vacillations and the battles between different mouldings and modalities may arise. It is the site for the nurturing of certain ways of living (often in opposition to the city) and a unique place where certain lives can be lived: those that are based on specific forms of scavenging and recycling, or those that rely on space and a proximity to the road. It is, finally, a living laboratory of separation and want, of social division, of concentration left and dispersion right, of great slits and small things that are made or created in the intervals and intermediate spaces between those, of ghettoisation, of a normativity different from that of the city, of an internal alterity (from modality to modality) and in opposition to the urban centre.
It combines equal measures of capitulation and riposte to the diktats of high-density speculators. It is frequently split by high-capitalism and land tenure. It is also moulded and demarcated by the road and the car. It overflows with a profusion of individual, collective and corporate forms of entrepreneurism and opportunism. It is a multidimensional and heterogeneous ‘place’; but also the expression of the presence, lack or incumbency of the State; and the manifestation of ‘freedoms’ that scribe, risk, force and adjust themselves.
If an initial 'image' of this suburban multimodality occurs, that will take the form of a tensor in opposition to (distending outwardly and inwardly), but in a vital relationship of interdependence with, the city centre. But internally, as well, as a network of tensors that pull, stretch and compress in different directions, creating 'events' many times only reconcilable in the production of new tensions (striations), or through sedimentation (soft) or suppression (hard): the intervention of local and State powers as an example of both; in the consolidation often brought to the informal villages, but also in the heavy-handedness of expropriation and demolition. If the city appears striated, this striation would be less marked than the great striae of the suburbs and suburbanity. 
And if a second image, half-closing our eyes, appears, this other will be of a chain of frequencies (polyphonic and dissonant, but distinct from an urban sound) that, thickening, envelopes the city and into it seeps, where the latter has overlooked the emission of its own sounds, or where the sounds it emitted to others, perhaps louder, have succumbed or by them have been suppressed. Here, we could mention forms that, belonging already in the city, are prone to suburbanisation, and the manner in which certain suburban modes import, transform and (re)export remodelled concepts and typologies. We would need a whole archaeology of city modes (that would already include expressions of suburbanity or a suburban potential) to find the threads of the process and sort this complex skein. As a primary example of a certain appropriation, metamorphosing and reselling, we would cite the shopping centre*; whose suburban origins pertain to the refashioning of the high street or the arcade (both urban) in a private and controlled suburban space that, in turn, is sold back to the city, competing with that same high street and the relics of the arcade (over these laid), in a tendency towards the privatisation of public space and the 'agoraisation' of private in substitution of the former.
* We refer here the adult age of an 'organism' whose maturing should be placed around the 1950s, by the hand of Victor Gruen, in the suburban commercial complex, roofed and acclimatised.
We should also elucidate the distinction between city and suburb, and this dichotomic instrument with which we operate over the conglomerate, following two different lines. First, through the verification of the several administrative, historical and geographical elements that demarcate a suburban ring around the city, and a city-suburb departmentalisation with defined coordinates and a specific normativity. And second, through the coalescing of a series of modes, which we consider suburban, given that they exist and predominate outside the centre and are largely placed in opposition to this - these would not be exclusive, in the same way that certain expressions of urbanity are not exclusive to the city. It would mean accepting a relatively rigid and pre-existent demarcation dividing city and suburbs, and above this superimposing a suburban modality that would complicate the demarcation, giving us an 'event', that of suburbanity, in expansion inwardly and outwardly, but also in transformation (to the point of occasional 'urbanisation'). In other words, to space we would add time.