The use of amphoras in the concrete vaults of buildings around Rome is a phenomenon that has been recognized for centuries largely because of the ruined state of some monuments that has left the amphoras exposed. The most renowned example is the Mausoleum of Helena, which by the sixteenth century was dubbed the “Tor Pignattara” from the visible remains of the amphoras (or “pignatte”) in its partially fallen dome (Fig. 47). The monument made such an impression in the past that it now provides the name for the surrounding suburban area. This technique of placing amphoras in the vaults has thus been long recognized, but it has sometimes been equated with or confused with another vaulting technique in which specially made terracotta tubes (tubi fittili) were inserted into each other to form the permanent centering of the vault. They are, in fact, two quite separate techniques. The amphoras are reused material within the vault whereas the tubes are made specifically to act as the permanent centering. The use of tubi fittili is a technique that only became common in Rome in the fifth century and later and is, therefore, beyond the scope of the present study. In the following discussion, I focus exclusively on the phenomenon of inserting reused amphoras into the core of the vaults.