As well as the devastating loss of human life in Saturday's earthquake, Nepalis, and the world, have lost parts of the country's unique cultural heritage.
Irina Bokova, the Director-General of the UN's cultural organisation, Unesco, said there had been "extensive and irreversible damage" at the world heritage site in the Kathmandu valley.
Seven monument zones in the valley make up the world heritage site.
The three urban zones at the site are Durbar squares - meaning "noble courts" - in the settlements of Kathmandu, Bhaktapur and Patan.
Ms Bokova describes these three complexes as "almost fully destroyed".
The four other zones are religious sites: Buddhist stupas [monuments] at Swayambhunath and Boudhanath and Hindu temple complexes at Pashupatinath and Changu Narayan.
Unesco said in a statement that it would be sending international experts to assess the damage to the sites in the Kathmandu valley.