The underground temple-well was discovered in 1972 during archeological excavations in the Pusto Garlo area in Greben Mountain near the village of Garlo. It is assumed that this is the oldest built temple in Bulgaria, probably Thracian. The hypothesis of its construction dates it to the XII-X century BC. Such facilities are extremely rare and atypical for the Balkans. In the 1980s, a restoration was carried out, which violated the authentic appearance of the building, as it aimed at socializing the site for visitors. Traces of an ax and animal bones were found in it, which speaks of sacrifices. There were many springs in the area and in the temple itself, so the temple is associated with a cult of water.
The underground temple-well is not socialized, there is no road or even a path next to it, nor are there any signs. He became somewhat famous after numerous publications on the Internet by enthusiasts.
The underground temple-well near the village of Garlo is an archeological site from the Bronze Age. It is an underground vaulted room built above a well. The temple-well is a round vaulted room, which can be reached by a corridor, 7 m long, and thirteen steps, and in its center is a 5-meter well.
According to scientists, this temple-well is similar to the "nugari" buildings that are typical of the island of Sardinia. This similarity is the reason for the dating of the site. So far, no other similar facilities have been discovered in the Balkans. According to some researchers, the temple served not only as a sacred place but also as an observatory for observing celestial bodies.