Immerse yourself in the city's history starting from Piazza Navona, one of the most charming and popular squares in Rome. The most beautiful parts of Piazza Navona are its three fountains, designed during the papacy of Gregory XIII. Erected in the center of Piazza Navona, the Fontana dei Quattro Fiumi was designed by Bernini in 1651. After a look over Piazza Navona, you'll enter into the subterranean world beneath the streets of this square which is built over the site of the Stadium of Domitian. The stadium was used almost entirely for athletic contests, and for a brief period following fire-damage to the Colosseum in 217 A.D., it was used for gladiator shows. From the Stadium of Domitian you will go back on the street to move onward to the Pantheon. According to Roman legend, this is the place where at his death, the founder of Rome, Romulus, was seized by an eagle and taken off into the skies with the gods. From the Pantheon to the Secret Bath of Neptune you will have just the time to take a breath before entering into the Basilica of Neptune, built in Rome by Marcus Vipsanius Agrippa in honor of Neptune. Next, travel to the Trevi Fountain and throw a coin in the water, adhering to tradition. Following the fountain, you'll enter into the subterranean world of Vicus Caprarius, also known as the City of Water. In this underground archaeological area of Vicus Caprarius you will find an intricate labyrinth of ancient remains: the remains of a domus of the imperial era; the castellum aquae of the Aqua Virgo aqueduct.