Great monuments are destroyed by war all the time. The White House was burned down in 1814. Before Hitler took France resistance fighters cut all the elevator cables on the Eiffel tower so Hitler could not easily fly a Swastika flag on the monument. Hitler ordered the city and the tower to be destroyed but his soldiers would not carry out the order. Countless buildings, monuments, museums, and relics are lost to us forever thanks to wars. As for modern day, many terrorist would love to make a mess out of our treasured sights, we have our Governments to thank for our safety at those spots so far. At some point the bad guys will get lucky again though. It is only a matter of time.