A boy stands inside a collapsed historical building at the Old City of Sanaa in Yemen, on March 21, 2013. The Old City of Sanaa was declared a world heritage site by the United Nations Educational, Scientific and Cultural Organization [UNESCO] in 1986. But UNESCO has recently threatened to remove the city from the list of protected sites, if the Yemeni authorities do not do more to prevent the destruction of old buildings in favor of new, cement ones. The Old City of Sanaa made up of some 6,000 buildings, including distinctive multi-storey tower houses. Built of rammed earth before 11th century AD, they are adorned with painted white filigree motifs. [Xinhua/Mohammed Mohammed]