Ara Pacis Museum

Architect Richard Meier's Ara Pacis Museum is the only major contemporary structure to have been built in the historic center of Rome since World War II.
If you were living in Rome 2,000 years ago, you would now be very, very old. But also importantly: you would've been alive during the time of Augustus, the first Roman Emperor (and grand-nephew of Julius Caesar).
His reign ushered in a period known as the Pax Romana (The Roman Peace) a two-century long period when the Roman Empire was largely free from large-scale conflict.
The Ara Pacis ('Altar of Peace') was Augustus's way of declaring his commitment to peace. See the 'Altar of Peace', originally inaugurated in 9 BC and then buried for centuries, plus loads more as you walk right into living history.