Temple of Vesta

The Temple of Vesta was built in the 7th Century B.C.E. by Numa Pompilius. This temple is the remnant of a late Etruscan Temple which is most noticeable by its circular shape. It was guarded by the Vestal Virgins and important documents such as Senators will were kept inside. The use of Corinthian Columns and marble also shows the effect of Greek architecture on the people of Rome.

http://en.wikipedia.org/wiki/Temple_of_vesta