Northwest section of the Topčider is declared a geological natural monument of "Senonian ridge of Mašin Majdan". The location is an archaeological excavation site as the fossils of the Mesozoic fish have been found in the sediment layers from the Late Cretaceous. It was named "Mašin majdan" ("Maša's quarry"), after a quarry owned by Mrs. Maša Dimić who lived in the house above the quarry. It was operational until the 1920s and the stone from the quarry was used for the villas on Topčider and Dedinje, but also for the construction of the nearby railroad. On the location of the former quarry, the Topčider summer stage was built in 1947. It had 1,800 seats and an excellent acoustics, being embedded into the limestone rocks. A project of Rajko Tatić, despite occasional public actions for its restoration (1999, 2009), by the 2010s the facility was abandoned and deteriorated. The summer complex includes a restaurant, built in 1950, and several auxiliary objects, designed by Radivoj Gibarac.