The first time I went to Rome a friend advised me to stay in a hotel on the piazza in front of the Pantheon. And so I did. What a great spot, what a wonderful neighbourhood. I add some pictures from the nearby area (they used to sell clothing for religious people, I don't know if they still do).
I am currently just adding pictures without captions, feel free to write a caption - as comment - yourself. I quote from the Enc. Britt.: Pantheon: building in Rome that was begun in 27 BC by the statesman Marcus Vipsanius Agrippa, probably as a building of the ordinary classical temple type—rectangular with a gabled roof supported by a colonnade on all sides. It was completely rebuilt by the emperor Hadrian sometime between AD 118 and 128, with some alterations made in the early 3rd century by the emperors Lucius Septimius Severus and Caracalla. It is a circular building of concrete faced with brick, with a great concrete dome rising from the walls and with a front porch of Corinthian columns supporting a gabled roof with triangular pediment. Beneath the porch are huge bronze double doors, 24 feet (7 m) high, the earliest-known large examples of this type.
The Pantheon is remarkable for its size, its construction, and its design. The dome was the largest built until modern times, measuring about 142 feet (43 m) in diameter and rising to a height of 71 feet (22 m) above its base. There is no external evidence of brick arch support inside the dome, except in the lowest part, and the exact method of construction has never been determined. Two factors, however, are known to have contributed to its success: the excellent quality of the mortar used in the concrete and the careful selection and grading of the aggregate material, which ranges from heavy basalt in the foundations of the building and the lower part of the walls, through brick and tufa (a stone formed from volcanic dust), to the lightest of pumice toward the centre of the vault. In addition, the uppermost third of the drum of the walls, seen from the outside, coincides with the lower part of the dome, seen from the inside, and helps contain the thrust with internal brick arches. The drum itself is strengthened by huge brick arches and piers set above one another inside the walls, which are 20 feet (6 m) thick.