The Old City of Sanaʽa () is recognised as a UNESCO World Heritage Site. The old fortified city has been inhabited for more than 2,500 years and contains many intact architectural gems. The oldest, partially standing architectural structure in the Old City of Sanaʽa is Ghumdan Palace. The city was declared a World Heritage Site by the United Nations in 1986. Efforts are underway to preserve some of the oldest buildings some of which, such as the Samsarh and the Great Mosque of Sanaʽa, is more than 1,400 years old. Surrounded by ancient clay walls that stand  high, the Old City contains more than 100 mosques, 12 ''hammams'' (baths), and 6,500 houses. Many of the houses resemble ancient skyscrapers, reaching several stories high and topped with flat roofs. They are decorated with elaborate friezes and intricately carved frames and stained-glass windows.