Valle Borghesiana is an area outside the ring road and lies between Via Tiburtina and the Rome-Naples motorway; the territory has a pretty residential character, and it is largely made up of a sprawling fabric of illegal houses. In this sense, the ensuing crossbreeding between the palazzina and the villino – two typologies arising from the reduction of the classical models of the palazzo and the villa – is merely the response to a more general and universal condition, in which individual dwellings are also called upon to play a political and productive role in the city. With this in mind, the project focuses on a 500×500 metre area in Valle Borghesiana, filling some unbuilt lots with thirty examples of 20th-century villas: a catalogue of canonical modern buildings, from Le Corbusier’s Villa Savoye to Robert Venturi’s Vanna House, from Peter Eisenman’s House XI to Rem Koolhaas’s Villa Dall’Ava. By contrast to the Valle Borghesiana houses, the new buildings all face outwards, showing how the house project cannot but turn into a street project, being the fundamental matrix of every urban dimension. Therefore, the thirty new villas erected in the Valle Borghesiana case study not only focus on the interior dwelling space, but project towards the city, showing how architecture is a recyclable, collective and essentially urban device.