The Mirage Tower - Pokemon Emerald

The Mirage Tower can be found in the Desert Part of Route 111. I say "can be found", because the Tower only appears rarely. You need to enter the Desert from the Northern Half of Route 111, making sure you have the Mach Bike and a Pokemon with Rock Smash. The Mirage Tower vade in and out of sight once entering the Route rarely, so if you don't see any disappearing & reappearing tower, you need to try again later. If you do see the Mirage Tower, you need to quickly make your way to the front door and go inside before it disappears again.

The Mirage Tower has 4 floors, the ground floor you just need to climb the ladder in the north-side on the floor. The second floor you need to work your way round anti-clockwise around the room, using the Mach Bike to quickly ride across the weak floor panels, staying too long on the panels will cause the floor panel to break and you will fall to the floor below. The third floor you need to break a boulder using Rock Smash to climb the ladder into the top/left of the room. On the top floor there is the Claw Fossil & Root Fossil. You can only choose one, the other will fall down into the shifting sands. The Claw Fossil can be turned into Anorith & the Root Fossil can be turned into Lileep.

The Mirage Tower