The basic Petra tour takes you from the gates of the site, down the 800 metre path to the start of the Siq Canyon, past the first small, intricate examples of Nabataean tomb construction. You then enter the 1.2 kilometre Siq, which is so much more than just the access point to the hidden city. Geologically it is hugely impressive, with the towering sandstone walls rising high above you; in places the canyon is so narrow the walls almost seem to touch. All along the Siq are altars and carvings in the rock, and in places the original cobbled paving has been excavated as well. Evidence also remains of the intricate drainage systems the Nabataeans used to convey water into the city. As you approach the end of the Siq, the excitement mounts as you wait for that first famous glimpse of The Treasury tomb, a narrow sliver visible, framed by the mouth of the canyon. No matter how many times you have seen it on film and in photographs, it still doesn’t disappoint. The Treasury is one of the most impressive tombs in the city, the detailed carving and relief climbing most of the way up the vast rock wall. It’s the perfect place for your guide to explain some of the principles of Nabataean architecture before leaving you to explore the rest of the city at your leisure.