BEIRUT — A landmark mosque in Aleppo was burned, scarred by bullets, and trashed — the latest casualty of Syria’s civil war — and President Bashar Assad ordered immediate repairs on Monday to try to stem Muslim outrage at the desecration of the 12th century site.

The Umayyad Mosque suffered extensive damage, as has the nearby medieval covered market, or souk, which was gutted by a fire that was sparked by fighting two weeks ago. The market and the mosque are centerpieces of Aleppo’s walled Old City, which is listed as a UNESCO World Heritage site.