The Ulpian Libraries were part of the great imperial Forum of Trajan, built into the Quirinal Hill. This forum also included the Basilica Ulpia.
Photo: Computer reconstruction by John Burge et al, University of Chicago
Founded in 114, the two libraries faced one another across a courtyard. Each contained about 20,000 scrolls. The West library was devoted to works in Greek, and the East one to Latin writings.
Between them stood, and still stands, the Column of Trajan. The Bibliotheca Ulpia was perhaps the most famous of the Roman libraries. It is thought to have survived until at least the mid-fifth century CE.