Kathmandu: Nepal's centuries of architectural heritage having historic importance in the Kathmandu Valley were reduced to rubble in just 80 seconds by a powerful earthquake last week that left over 6,000 people dead.

"A total of 57 monuments of the Kathmandu Valley have been destroyed," said Bhesh Dahal, Director General of the Department of Archaeology. "Our team is currently on the field to make the deeper inventories," he was quoted as saying by the Nepali Times.

Nepal earthquake: Centuries of architectural heritage gone in 80 secondsNepalese soldiers line up to clear rubble of temples at the Patan Durbar square in Kathmandu on May 1, 2015. Pic/AFP

Several historic temples and ancient palace complexes destroyed in a 7.9 magnitude Richter scale quake on Saturday were also damaged in the 1934 temblor, and hastily rebuilt. The temples and palaces have frequently been destroyed every 100 years or so, and they have always been rebuilt.

Six days after the quake, it is apparent that many monuments in Bhaktapur, Patan, Kathmandu, Kirtipur, Bungamati, Khokana and Sankhu have been destroyed, the paper said.

Kathmandu's 19th-century nine-storey Dharhara tower and Darbar Square, a UNESCO World Heritage site, were completely damaged in the quake.

"Swota's Rada Krishna Temple came down like a house of cards on Saturday," said Rohit Ranjitkar of Kathmandu Valley Preservation Trust (KVPT).

The KVPT has tried to collect all the artefacts from the damaged monuments before they are stolen or damaged further. "Volunteers have been collecting carved wooden columns and eaves, stone and bronze figures of deities and putting them inside the Patan Museum courtyard for safekeeping. In Bhaktapur, the community is involved in protecting the ruins, and making an inventory of the damaged monuments," it said.

The Patan Museum courtyard, parts of the Hanuman Dhoka Complex, restored temples and the 'floating' Taleju Temple in Patan remained largely unscathed. The Nyatapola Temple in Bhaktapur and Patan's Krishna Mandir survived 1934, and 2015 as well, the paper said.