The line for the constantly frozen ground is moving down. Here inside the Peter Melnikov Institute of Permafrost, Leonid Gagarin shows it's current depth. The institute monitors the depth of the frozen ground and sets building standards for building on permafrost. The subsidence of large buildings into the ground can be prevented by using stilts extending down to about fifteen meters or more. At this depth the temperature does not change with the seasons, remaining at about -5 °C (23F).