The first modern construction in Rome's historic centre since WWII, Richard Meier's controversial and widely detested glass-and-marble pavilion houses the Ara Pacis Augustae (Altar of Peace), Augustus' great monument to peace. One of the most important works of ancient Roman sculpture, the vast marble altar – measuring 11.6m by 10.6m by 3.6m – was completed in 13 BC.
The altar was originally positioned near Piazza San Lorenzo in Lucina, slightly to the southeast of its current site. The location was calculated so that on Augustus' birthday the shadow of a huge sundial on Campus Martius would fall directly on it. Over the centuries the altar fell victim to Rome's avid art collectors, and panels ended up in the Medici collection (see the garlanded reliefs embedded in the walls of the Villa Medici), the Vatican and the Louvre. However, in 1936 Mussolini unearthed the remaining parts and decided to reassemble them in the present location.
Of the reliefs, the most important depicts Augustus at the head of a procession, followed by priests, the general Marcus Agrippa and the entire imperial family.