Temple of Jupiter Stator

You see an old and venerable temple dedicated to the god Jupiter Stator ("the Stayer"). Near the temple is a very old gate, the Porta Mugionia (Cattle-gate, literally "mooing gate"), dating back to the original fortifications of the city on the Palatine. According to legend, Rome's founder and first king, Romulus, vowed a temple to Jupiter if his troops could stand their ground against the Sabines at this gate. The battle was successful and the land was consecrated, but the temple was not actually built until Jupiter helped another Roman, the consul M. Atilius Regulus, hold his position against the Samnites in 294 BCE. Hence this title of Jupiter, who "stands firm" or "stays the course."

The above relief, from a second-century CE grave monument of the Haterii family, is thought to represent the Temple of Jupiter Stator, though the actual remains of the temple have not been found and its precise location is still disputed.