Petra is known as Jordan’s most valuable treasure and greatest tourist attraction. It is a vast, unique city, carved into the sheer rock face by the Nabataeans, an industrious Arab people who settled here more than 2,000 years ago, turning it into an important junction for the silk, spice and other trade routes that linked China, India and southern Arabia with Egypt, Syria, Greece and Rome. Entrance to the city is through the Siq, a narrow gorge, over one km in length, which is flanked on either side by 80-metre-high cliffs. There are hundreds of elaborate rock-cut tombs with intricate carvings. There is also is a massive Nabataean-built, Roman-style theatre, which could seat 3,000 people. Petra also has two museums; the Petra Archaeological Museum, and the Petra Nabataean Museum. A 13th century shrine can be seen on top of Mount Aaron in the Sharah range.