The original World Heritage site consisted solely of the defences and the intra-mural city. It was later extended to include the Pile medieval industrial suburb, a planned development of the 15th century, and the Lovrijenac Fortress, located on a cliff, which was probably begun as early as the 11th century, but owes its present appearance to the 15th and 16th centuries. Also included were the Lazarets, built in the early 17th century to house potential plague-carriers from abroad, the late 15th-century Kase moles, built to protect the port against south-easterly gales, and the Revelin Fortress, dating from 1449, which was built to command the town moat on its northern side.