The National Roman Museum – Crypta Balbi occupies three floors and is located in the buildings that are part of the of the Medieval and Renaissance complex that rose on the structures of the Theatre and of the crypt built by Lucius Cornelius Balbus in 13 BC. 

The ground floor illustrates the transformations performed on the block of buildings from the Roman Age to our days. There are many materials found during the excavations and a rich and thorough didactic apparatus. The second and third floors are dedicated to the evolution of the urban culture between the fifth and the tenth century AD and highlight various aspects of Rome in the late-ancient, Byzantine, and early Middle Ages. 

This last period is not very documented and now some light is being cast on it. The materials exhibited come from the Fora, the Palatine, the Porticus Liviae on the Colle Oppio, the Basilica Hilariana on the Caelius , the Conservatory of San Pasquale in Trastevere, in addition to the Crypta Balbi (in particular from the Exedra that has given back thousands of findings of works performed in an eighth century workshop. 

Other materials come from the historical collections of the National Roman Museum, in particular from the collections of the former Kircherian Museum and the Gorga and Betti collections. Lastly two maps with the topography of Rome in the Late-ancient and Medieval Ages and a map that shows the locations in the city where the archaeological excavations regarding this specific period of time are exhibited in a hall.