Between August 2015 and April 2016, the Hal Saflieni Hypogeum will be closed to the public so that a conservation project, which is being financed through the EEA Grants 2009-2014, could take place, Xinhua learned from "Heritage Malta" on Saturday.

The Hal Saflieni Hypogeum in Malta is an enormous underground prehistoric cemetery that was used from around 4,000 BC to 2,500 BC. Since it is considered as a unique testimony to a civilization which has disappeared, in 1980 this site was included in the World Heritage List by UNESCO.

This hypogeum was discovered in 1902 and once excavated, it was found that it had been hewn in the globigerina limestone rock in the form a superimposed structure of three levels.

The oldest of the three levels is the uppermost and it was dug in a hill. Inside this level, several openings and chambers were cut out in the rocks in order to bury the dead.

The site was first opened to visitors in 1908 and since then it has been visited by thousands of people. However, regretfully, this had a negative impact on the delicate microclimate of the area which resulted in serious preservation issues.

In fact, between 1990 and 2000, this hypogeum was closed to the public in order to allow proper conservation measures to take place. Meanwhile, the project included also the acquisition and dismantling of houses which had been built above the site.

Once re-opened, new regulations established that only 10 visitors an hour could be allowed in the hypogeum, for a maximum of 8 hours a day. This arrangement was complemented by an environmental control system which keeps temperature and humidity at required levels.

According to Heritage Malta, which is responsible of Hal Saflieni Hypogeum, the principal challenge of this site is to maintain a stable climatic condition. Therefore, from time to time, this prehistoric area requires to be inspected in order to assess its condition in terms of conservation, geology and organic residues.