Emphasis on often: The AREA team was able to purchase about 100 square feet of marble remnants from a local yard for just €300, an incredible boon to the overall project cost.

It is one of two remaining original structures on Coliseum Square. Marble steps lead into the 1856 home, renovated over the past eight years into a showplace on the market for $3.1 million.

And a 23-square-foot black marble spa with a whirlpool bath and an infrared sauna. (Lacking Corbusier’s sea view, the apartment instead has a fancy tub.) ...

While these are on display year-round to visitors, the 1,300 square-metre marble floor is only uncovered for two short periods each year. These coincide with Siena’s centuries-old Palio horse ...