Burj Al Arab - one of the world's most luxurious hotels - aside from all the mystique and wealth it's known for, also has the highest tennis court in the world. Its space, located at 210 metres of altitude can also become a heliport for emergency landings or guest traffic.
Another extravagance from this sumptuous hotel, in Dubai, to which very few mortals have access. I confess, even if I was given access to it, I would have some difficulty in running around after a tennis ball at 210 metres above the ground.
Here's a video of Andre Agassi playing with Roger Federer. The view is breathtaking.
Here are some pictures of the interior of this piece of heaven on earth.