Sheik Zayed Grand Mosque is in the top ten for largest mosque in the world, and sits just outside Abu Dhabi. It is ornate and beautiful and well worth a visit, and you are allowed to go inside even if you are not a Muslim.
The Burj Al Arab is the world's only six-star hotel. It stands on a manmade island near Jumeriah Beach. It is built to look like the sail of a ship out in the sea.