The Forum Boarium was the area between the Tiber and the Capitoline, Aventine and Palatine hills in Rome. It was used to host a cattle market. It was the Etruscans who had developed the land in the 6th century B.C. by constructing a great sewer, the Cloaca Maxima, in this marshy area. Some of the arches of the Cloaca Maxima can still be admired.
Forum Boarium Rome
Servius Tullius built the Tiber port in this period. There are two temples facing the Tiber, which date back to the time of the Republic. The rectangular one was dedicated to Portunus (a river God), whereas the round one was dedicated to Hercules.
According to legend, The giant Cacus robbed Hercules of his cattle when the latter arrived in the area. Hercules killed Cacus and henceforth was honored as a God by the people who lived on the Capitoline Hill. These Arcadians also dedicated an altar, the Ara Maxima, to Hercules. The core of this altar, made of tufa stone, can be seen in the church of Santa Maria in Cosmedin (of Mouth of Truth fame).
During the Trajan period warehouses were built near the port, while the Arch of the Argentari was constructed during the reign of Severius and the the Arch of Janus during the reign of Constance II.