[custom_adv] Whether or not they wanted to, airlines are prohibited from entering Mecca and, particularly, flying over the Holy Kaaba. It all has to do with religious custom. Non-muslims are not permitted to travel to Mecca since it is a sacred place for the Islamic faith and centre of the Hajj pilgrimage. [custom_adv] As it is, aircraft are not allowed to fly over Machu Picchu. Not only is it a site of cultural significance but it also has a delicate balance of nature which is best left untouched. The danger with flying commercial aircraft over the region is that should any aircraft crash or have an emergency landing in the region it would undoubtedly damage the precious ecosystem. [custom_adv] Much like flying over Machu Picchu, the reason that passenger aircraft steer clear of the Parthenon in Athens is to protect this historical wonder. Whilst aircraft are permitted to fly over this monument, they must give it a wide berth. [custom_adv] The UK’s Downing Street is perhaps one of the most significant streets in the entire country. It’s home to the serving Prime Minister and access to this gated location requires special permissions. [custom_adv] Similar bans to protect people from future aircraft-based terrorist attacks have also been placed in the airspace above stadiums in the US which seat more than 30,000 visitors. That would include many sports venues around the country.