Providence, Rhode Island has a large Italian-American population, but not many people realize that the One BankBoston Plaza, which dominates the city's skyline, is Italian-American, too. The tower, originally the Hospital Trust National Bank tower, was built between 1970 and 1974. The white, porous-looking rock that covers the outside of the building and the walls of the lobby is travertine from the Bangani di Tivoli quarry in Italy.
Tivoli is a city just east of Rome.
It sits on top of huge deposits of travertine, which people quarry
and export for building and decorative stone. Tivoli is also famous
for the villa of the emperor Hadrian and the Bagni di Tivoli--hot
springs that have attracted tourists since the days of the Roman
empire.
Travertine is a type of limestone that forms at hot springs. Italy is full of hot springs and volcanoes. It is ramming into Europe as the African plate moves north and collides with the European plate. Such a collision generates a lot of heat. Tivoli sits at the southern end of a chain of inactive volcanoes with lakes in their craters. When the volcanoes were still active, hot magma under the area heated groundwater, which dissolved the overlying limestone. When the hot water reached the surface and cooled, the calcium carbonate precipitated out again. Over time, this formed massive travertine beds. The Romans used travertine from Tivoli to build the Colosseum and many other structures that are still standing after a thousand years or more.
