The Ara Pacis Augustae (Altar of Augustan Peace), also called the "Ara Pacis," is a famous Roman monument housed in the Museo dell'Ara Pacis, in Rome, Italy. Built between 13-9 BCE, it is widely considered to be one of the most beautiful of all Roman monuments. Here, you can view high-resolution beautiful images and access 3-D models of what the Ara Pacis looked like during Rome's apogee.
The website, created by professors of Reed College in the United States, is a great resource and is available in English, Italian, German, French, Spanish, Portuguese, Russian, Japanese, Chinese, and Korean. Take your pick and enjoy!