Located in the ancient Forum Boarium near the Tiber river, the Temple of Portunus is a well-preserved example of ancient Roman architecture. The temple overlooked the fluvial port of Rome, watching over the goods entering the city.

The small temple, which is raised on a podium, is a pseudoperipteros. Four free Ionic columns are located on the portico, while the other columns are connected along the walls of the cella. The temple dates back to the 1st-century and was dedicated to Portunus, the Roman god of doors, keys, and livestock, but for centuries it was thought to be dedicated to Fortuna Virilis, a manifestation of the goddess Fortuna.  

Utilized for centuries, the temple was abandoned with the closure of all pagan temples across the Roman Empire during the 4th-century. In 872, the temple was turned into a church while retaining its external appearance. The church was dedicated to Saint Mary of Egypt, the patron saint of penitents. In 1916, the church was closed and the building was reestablished as a Roman temple.