Walk down the back of the Van Fortress rock and you reach a wide, level plain dotted with low stone foundations and the ruins of two large mosques — the Hüsrev Paşa and Kaya Çelebi mosques, both Ottoman, both still partly standing. This is the site of Old Van: until 1915, a city of around 80,000 people, predominantly Armenian, with two cathedrals, dozens of churches, and a famous bazaar.
The site is open and free. The foundations of streets and houses can still be traced in the grass; in places, scattered pieces of carved stone and pottery come up out of the ground. It is a quiet, melancholy place that no one explains to you on site — which makes some advance reading useful before you visit.