During a U.N. Educational, Scientific and Cultural Organization visit to Timbuktu from May 28 to June 3, international and local experts found 14 of Timbuktu's mausoleums were destroyed, the United Nations said in a release.
Lazare Eloundou Assomo of UNESCO's World Heritage Center said the damage is "even more alarming than we thought."
Fighting between government forces and Tuareg rebels also destroyed the Djingareyber Mosque, widely thought to have been built around 1327, mostly out of straw and wood, the release said.
The El Farouk independence monument at the entrance of the city was also destroyed and an estimated 4,203 manuscripts from the Ahmed Baba research center were lost.
"An estimated $11 million has to be found to begin work as soon as possible," Assomo said of the rehabilitation and preservation work on the damaged sited.
"UNESCO saved the temples of Egypt and rebuilt the Mostar Bridge," UNESCO Director-General Irina Bokova said. "UNESCO will rebuild the mausoleums of Mali."