The center of the Ukraine is a part of a very old continent which formed 2.8 to 3.7 Ga ago. Actually, this Sarmatian Craton was split into two parts, the big forming the center of the country and a smaller piece along the northeastern border. But as cratons are made of very old metamorphic rocks which are not suitable for the formation of caves, we have only a single show mine and some subterranea listed in this huge area. Actually, there are only two areas with a certain number of caves, but both are quite spectacular.
The Crimean Mountains or Yayla Mountains are located at the southern coast of the Krimean peninsula. They are running parallel to the coast, have a lot of limestone and spectacular karst caves, including several show caves. The limestone and the geography were also suitable for the construction of cave cities and cave monasteries. The caves were excavated into the cliff side and connected by trails above ground. The main purpose of those constructions was safety, the area was in turmoil since Roman times, and this has not stopped in the present.
The second is the gypsum karst in the western part of the country. Massive layers of gypsum are located right beneath the surfaces and have numerous huge labyrintine cave systems. Some of the systems are water-filled.