A volcanic crater, even one with an extinct volcano is fascinating. The Nemrut crater, not far from lake Van is also pretty stunningly beautiful, particularly in autumn. Above is a little video of the drone flying above some of the orange and yellow trees inside the crater.
Van is not the kind of city you'd hang out in without a reason. At least not me. Considering that Van doesn't really have any famous attractions and it's in Turkey, a country with possibly more historic monuments and beautiful scenery than… well anywhere I can think of except India, why would you want even visit