Like its 2nd - century model , the library is a round building fronted by a large two - storey portico which forms the main entrance on St Peter 's Square .
Like its 2nd - century model , the library is surrounded by five bays of Corinthian columns .
Like its 2nd - century model , the library is a round building fronted by a large two - storey portico which forms the main entrance on St Peter 's Square , and is surrounded by five bays of Corinthian columns .