A meteorological station was built at the top in 1935, and is still operating. The station also serves as a rest shelter for hikers and is the headquarters for the mountain rescue team. Historical documents show that several centuries ago Vitosha mountain was still covered by the remains of the inaccessible "Great Bulgarian Forest" ("Magna Silva Bulgarica"). Today, the natural coniferous forests of Vitosha remain only in the reserve Bistrishko Branishte and around Zlatnite Mostove (The Golden Bridges). The Golden Bridges is a stone river consisting of a ribbon of huge boulders running down the mountainside. This scenic spot is located along the Vladayska River in an area of mixed deciduous and evergreen forest. However, this is only one of the stone rivers found in Vitosha and they were once the moraines of ancient glaciers. Their further formation occurred due to the spherical erosion of the sienite rocks and their gradual movement to down stream valleys by the forces of gravity and moving water.