3 Best Sights in Piazza di Spagna, Rome

This pristine monument sits inside one of Rome's contemporary architectural landmarks: a gleaming, rectangular, glass-and-travertine structure designed by American architect Richard Meier. It overlooks the Tiber on one side and the ruins of the marble-clad Mausoleo di Augusto (Mausoleum of Augustus) on the other and is a serene, luminous oasis right in the center of Rome.

This altar itself dates from 13 BC and was commissioned to celebrate the Pax Romana, the era of peace ushered in by Augustus's military victories. When viewing it, keep in mind that the spectacular reliefs would have been painted in vibrant colors, now long gone. The reliefs on the short sides portray myths associated with Rome's founding and glory; those on the long sides display a procession of the imperial family. Although half of his body is missing, Augustus is identifiable as the first full figure at the procession's head on the south-side frieze; academics still argue over exact identifications of most of the figures. Be sure to check out the small downstairs museum, which hosts rotating exhibits on Italian culture, with themes ranging from design to film.

The huge white mass known as the "Vittoriano" is an inescapable landmark that has been likened to a giant wedding cake or an immense typewriter. Present-day Romans joke that you can only avoid looking at it if you are standing on it, but at the beginning of the 20th century, it was the source of great civic pride. Built to honor the unification of Italy and the nation's first king, Victor Emmanuel II, it also shelters the eternal flame at the tomb of Italy's Unknown Soldier, killed during World War I. Alas, to create this elaborate marble behemoth and the vast surrounding piazza, its architects blithely destroyed many ancient and medieval buildings and altered the slope of the Campidoglio (Capitoline Hill), which abuts it.

The underwhelming exhibit inside the building tells the history of the country's unification. The Vittoriano has a rooftop terrace, however, that offers some of the best panoramic views of Rome.

Inspired by Trajan's Column, this 2nd-century-AD column is composed of 27 blocks of marble covered in reliefs recounting Marcus Aurelius's victory over the Germanic tribes. A bronze statue of St. Paul, which replaced the original effigy of the emperor and his wife, Faustina, in the 16th century, stands at the top. The column is the centerpiece of Piazza Colonna.