PRAGUE (Reuters) - Restoration experts in the Czech Republic have been set an unusual task - to dismantle four towering pyramids made up of centuries-old bones from more than 40,000 human bodies, clean them up and then reconstruct them as before.

The restoration project, expected to last two years, is aimed at preserving the bones, the chief attraction at the Sedlec ossuary church, a site on the outskirts of the mediaeval mining town of Kutna Hora in the central Czech Republic.

The project also aims to restore and strengthen the church building which houses the bones and skulls.

The site, which draws half a million visitors every year, not only features the four large pyramids of bones - it also boasts a chandelier, a coat of arms and various other decorations made from every bone in the human body.

“Many people find it weird today and come to see this as some dark spectacle, a house of horrors,” said Radka Krejci, in charge of operations at the local parish.

“But we do not want it to be perceived like that, it is a place of reverence, a burial place.”

The bones came from a cemetery adjacent to a monastery founded by the Cistercian order in 1142.

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The burial ground was enlarged during a plague epidemic in the 14th century. In 1318, about 30,000 people were buried here and more joined them in the 15th century during religious wars between Roman Catholics and the Hussites.

A lack of space prompted the decision to exhume the bones and place them in a depositary, one of a number of such sites around Europe, during the 16th century. Legend says that a half-blind monk built most of the bone structures.

The present appearance of the bone structures dates from 1870 and is the work of Czech wood-carver Frantisek Rint, who added the various decorations to the original pyramids.

The renovation is necessary due to the aging of both the bones and the ossuary.

“The bones will be cleansed of surface dirt and then soaked in lime solution. This is a natural method of preservation which was also used during the creation of these pyramids,” said conservation expert Tomas Kral.

To make sure the structures are rebuilt in the original format, the restoration team has hired a firm, Nase Historie, to produce computer models of the bone pyramids using photos and videomapping.