It might happen again. Back in 2001, the Talibans destroyed the Bamiyan Buddhas, as they thought the magnificent statues promoted idolatry:(:(. Now, some of Islam's historic sites in Mecca, possibly including a home of the Prophet Mohammad, are under threat from Saudi real estate developers and Wahhabi Muslims who view them as promoting idolatry:(.

Bamiyan Buddha, prior to destruction (Courtesy: Pratyeka)Sites such as this belong to the whole world. It really does not matter if you believe or not believe in that particular religion or ideology; the sites represent important events in world history. By some perverse logic, the Saudis have not allowed preservation of old buildings, especially those related to the prophet. They fear other Muslims will come to see these buildings as blessed and this could lead to polytheism and idolatry:)).
The Washington-based Saudi Institute, an independent news gathering group, says most Islamic landmarks have been destroyed since Saudi Arabia was founded in 1932. It cited a 1994 edict by the kingdom's senior council of religious scholars which ruled that preserving historical buildings might lead to polytheism.
The historic buildings might be destroyed to create a parking lot, and towers to house people who visit Saudi Arabia every year for the annual pilgrimage known as Hajj.
As long as such mindless morons (a.k.a. religious scholars) exist, there will be no peace in the world. Ironically, the biggest monuments to Islam are its mosques, and the Kaaba (black cube-like structure) in Mecca. I wonder if the Islamic purists would consider those monuments 'un-islamic' as well;).