Egyptian authorities have put a ban on idling vehicle engines in Saqqara, south-west of Cairo, after cracks started to show on the country's oldest pyramid.
The head of Egypt's supreme council for antiquities, Zahi Hawass, had "decided to ban the running of engines of all cars and buses waiting for tourists in the archaeological area of Saqqara", a council statement said.
"The running of engines has caused the area to experience some shaking which has in turn caused cracks in the pyramid of Djoser," the statement said.
Huh. They quit having tour busses get near the Valley of the Kings several years ago for fear the engine and rumbling of them would start to crack many of the tombs. They might have limited bus access to the Giza site too, if memory serves (I might be thinking of the tourist vendors though).