He had the Villa d'Este built in Tivoli by Mannerist architect Pirro Ligorio, to match the other palaces he was building in Rome.
Many of Ligorius' falsifications persist in the literature of the 17th and 18th century, e.g. the work of Marquard Gude and its later editions, but they were recognized by the mid 19th century.
Many other remains of buildings exist; they were more easily traceable in the 16th century when Pirro Ligorio and Antonio Labacco made plans of the harbour.