Perhaps most intriguing of all the branches of the National Museum of Rome, the Crypta Balbi houses the archeological remains of the vast portico belonging to the 1st-century b.c. Theatre of Lucius Cornelius Balbus, discovered on the premises in 1981. The first floor exhibits chronicle the history of the site through to the medieval period and the construction of the Conservatorio di Santa Caterina della Rosa. The second floor (“Rome from Antiquity to the Middle Ages”) explores the transformation of the city between the 5th and 9th centuries, using thousands of ceramic objects, coins, lead seals, bone and ivory implements, precious stones, and tools found on the site.