The most important monument of the city is Patan Durbar Square, which has been listed by UNESCO as one of seven Monument Zones that make up the Kathmandu Valley World Heritage Site. The seven monument zones were included in the World Heritage List in 1979 as one integrated site. The monument zones are declared as protected and preserved according to the Monuments Preservation Act of 1956. The Square was heavily damaged on 25 April 2015 by an earthquake.