Dan explores subterranean caves at Goreme. Then he travels on to Istanbul, where he visits the Hagia Sofia. Next up is Russia, where Dan is suitably impressed by the Moscow Metro, Solovki Monastery, and St. Petersburg. And on to Poland and Germany for more fascinating finds new and old.Dan explores subterranean caves at Goreme. Then he travels on to Istanbul, where he visits the Hagia Sofia. Next up is Russia, where Dan is suitably impressed by the Moscow Metro, Solovki Monastery, and St. Petersburg. And on to Poland and Germany for more fascinating finds new and old.