Image copyright Reuters Image caption A view of the collapsed Vatsala Durga temple in Bhaktapur

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.

Kathmandu's Durbar Square

Image copyright AFP Image caption Kathmandu's Durbar Square, shown in June 2011 - the nine-storey Basantapur Tower is on the right

Image copyright AP Image caption The same buildings in the capital's Durbar Square shown after the disaster - the Basantapur Tower's top tiers have collapsed

Image caption Another part of Kathmandu's Durbar Square, shown in 2010

Image copyright AP Image caption The quake caused the statue of Hindu god Garud to topple from its pillar

The Durbar Square in Kathmandu's Old City is a mesh of palaces, courtyards and temples.

Unesco calls it "the social, religious and urban focal point" of the Nepalese capital.

Bhaktapur's Durbar Square

Image copyright AFP Image caption Bhaktapur's Durbar Square shown in July 2011, with intact Vatsala Durga temple (grey stone)

Image copyright AFP Image caption After the earthquake residents are taking refuge in the open space of the square - behind them is the rubble of Vatsala Durga

The main temple in Bhaktapur's square lost its roof, while the 16th Century Vatsala Durga temple, famous for its sandstone walls and gold-topped pagodas, was demolished by the quake.

Patan's Durbar Square

Image caption This photo from 2010 shows the historic square in Patan with intact temples

Image copyright Rex Features Image caption Looking back in the other direction along the square after the earthquake, several of the tiered temples appear to have collapsed

Patan, or Lalitpur, is across the Bagmati river to the east of Kathmandu.

The city was founded in the 3rd Century.

Swayambhunath temple complex

Image caption The stupa at Swayambhunath religious complex, pictured in 2010

Image copyright EPA Image caption This image taken the day after the earthquake shows damage to the surrounding buildings

Image copyright EPA Image caption A monk salvages items from the rubble of a building next to the stupa

The Buddhist temple complex at Swayambhunath, founded in the 5th Century, has also been damaged.

Video footage showed the toppled facade of one of the buildings, with the prayer flags surrounding it still fluttering in the wind.

But the iconic central stupa, with its gazing eyes of the Buddha, still stands.

Boudhanath temple complex

Image copyright AFP Image caption The magnificent Boudhanath Stupa, shown in 2014

There are reports that the Boudhanath stupa has sustained some damage, though details are not yet clear.

It is the largest stupa in Nepal.

Pashupatinath Hindu religious complex

Image copyright AFP Image caption Bodies of earthquake victims are cremated at Pashupatinath on the banks of the Bagmati river

The shrine at the Pashupatinath Hindu religious complex has not been damaged in the disaster, a devotee at the temple told the Indian Express.

Cremations are being held on the site continuously, the paper reports.

Dharahara tower

Image copyright ALAMY Image caption Dharahara pictured before the earthquake

Image copyright EPA Image caption Saturday's disaster reduced the tower to rubble

This landmark has been reduced to a stump by Saturday's quake.

Built by Nepal's first prime minister in 1832, the site, also known as the Bhimsen Tower, was popular among tourists who would climb up more than 200 steps to view Kathmandu from the top.

It is unclear whether all of these ancient monuments can, or will, be rebuilt.

Historian Prushottam Lochan Shrestha told the ekantipur.com website: "We have lost most of the monuments that had been designated as World Heritage Sites in Kathmandu, Bhaktapur and Lalitpur [Patan].

"They cannot be restored to their original states."

And yet many buildings that were destroyed in Nepal's 1934 earthquake were reconstructed, including the Dharahara tower.