A corner of the Italian capital has been overrun – by objets, works in progress and upcycled antiques, that is. Rolf Sachs, armed with eternal optimism and a taste for the surreal, leads the charge of arty bric-à-brac, from exit-sign tables to bucket lights. For all the conquering chaos, the Swiss artist’s car park-turned-studio is still eloquent in the design principles of its prima lingua, with palazzo-inspired lime paste and crushed-brick floors seized from the ancient Romans