Now that you're past the cemetery you can actually begin to hike up the tower. Upon entering you'll be greeted by a member of the Litwick evolution chain and that Pokemon will guide you through the 20 different floors. Each floor will have a different challenge that you must complete. One failure and you'll be teleported out.
Located at the base of this endless tower is the only cemetery in the entire region, so getting past that is a journey in itself. However, it's just a kid's trip compared to hiking up the tower, which seems to literally go on forever.