Erected in 203. You can see it close up from Via della Curia also (without entering the Forum).
The temple of the Emperor Hadrian was consecrated in 145 AD by Emperor Antoninus Pius. The remains of the antique temple were incorporated into a new building that served as the Papal Customs House. It was finished around 1690 and today accommodates the Stock Exchange (Borsa).
A very ancient church named after a saint who was in 1969 removed from the Roman Catholic calendar of saints for the lack of details of her life. But the church retains the name and is well worth visiting for an excellent 4th-century mosaic and attractive decorations on the facade. Visiting hours are short, but if you arrive close to 11:30, try talking to the attendant if you see him, and he might let you visit for a few minutes. The church is small, so 15 minutes should be long enough to see and absorb everything.
On the other side of the Via dei Fori Imperiali to the Roman Forum. Well-preserved market area that doubled as a way of stopping the Quirinal Hill from collapsing. Below in the Forum is Trajan's Column, built in 113 with reliefs depicting the Emperor Trajan's vistories in battle.
Built in the 9th century, this ancient basilica crowns the top of the Esquiline Hill. Tons of gold decorate the interior together with impressive mosaics (particularly when the floodlights are turned on), and there is a museum on the premises. If you are in Rome on Corpus Christi (Corpus Domini), which is the Thursday after the 8th Sunday after Easter, an early-evening service is held in San Giovanni by the Pope followed by a procession along Via Merulana to Santa Maria. Good opportunity for a close up view of the Pope. This is a very large church with lots to see, as for example, the main part of the church has two layers of mosaics and paintings high on the walls, the altar and apse are spectacular, and then there are several more or less large chapels you won't want to miss, including the one with the amazing golden baptismal font. Allow at least an hour if not an hour and a half or more to visit the interior, even if you do not take any special tours, and also allow time to view the exterior from all sides. Overall, at least 2 hours would not be too much time to allot.
Good collection of Renaissance and Baroque art, including by Velasquez, Titian, Raphael, and Bernini, all owned by the Doria Pamphilj family. Excellent audio guides really bring the paintings to life.
Underground burial place of an ancient Roman family and of seven early popes.
Built in honour of Victor Emmanuel, the first king of a unified Italy, this vast structure may appear to be solid white marble but actually contains many rooms inside. There are two permanent museums, one on Italian Reunification and one on emigration from Italy, as well as other spaces that host rotating exhibitions. A walk through the Flag Room leads to the tomb of the unknown soldier. Good views from half-way up but you can also pay €10 (€2 concessions) and take a lift all the way to the top.