The ancient city of Petra, located in the heart of the mountainous desert of southern Jordan, had different approaches in the past. One possible route was from the south, across the plain of Petra and around Jabal Haroun or Aaron's Mountain. Another approach was from the high plateau to the north. But modern visitors approach Petra from the east, through a narrow gorge called the Siq, that ends dramatically in front of the elaborate ruins of the “Treasury” or Al-Khazneh in Arabic.

The Siq is not really a gorge because it was not formed by water erosion but by tectonic forces that caused the sandstone mountain to split in half creating a deep, narrow pathway. Later, water from flash floods gradually rounded the sharp edges of the gorge into smooth curves.

The first glimpse of the Treasury through the Siq. Photo credit: David Bjorgen/Wikimedia (left), txefo/Flickr (right)