When limestone is put under a lot of pressure for a long time (thousands of years), it can turn into travertine, the way peat turns into coal. If the travertine is left under pressure for thousands more years, it can turn into marble, the way carbon can turn into diamonds. So travertine is a kind of stone that is about halfway in between limestone and marble. It’s finer than limestone, but not as fine as marble.
This kind of stone is pretty soft – for stone – so it is pretty easy to cut and shape the way you want it for your building. But it is not as rare or expensive as marble. So it was popular – architects liked to be able to make a building look important without too much work or expense.
The Romans used travertine on the main parts of buildings where it was too expensive to use marble. Often, for instance, the steps might be made of travertine while the columns or sculptures were made of marble. We do the same thing on modern buildings today.
Some examples of Roman buildings that use this kind of stone are the Colosseum in Rome or the Theater of Marcellus.
Architects also used this white stone in the Middle Ages, for example to build the cathedral at Pisa, in Italy.
Did you find out what you wanted to know about Roman building stone? Let us know in the comments!
Learn by doing: find a building in your city that uses travertine
More about limestone
More about marble
Houses, Villas, and Palaces in the Roman World, by Alexander McKay (reprinted 1998). A standard text on Roman houses.