For the first time, in the spring of 1331 solar year, a group of the most famous mountaineers of Iran, members of the "Niro Rasti" club, discovered and visited Katlekhor cave. One of the Zanjani members of the mentioned group named Seyed Asadullah Jamali registered the cave. Since then, Katlekhor Cave has been the focus of cave climbing enthusiasts as a wonderful natural phenomenon.The building is located under the mountain of Katlekhor and from the mouth of the mouth of the river Shur, which is one of the sub-branches of Qezaluzen, flows. The cave was created in a rectangular area with dimensions of 2000x1500 meters. In the mentioned place, the action of mechanical weathering and internal forces with the help of each other have created a number of cracks or intersecting faults in the inner limits of this space and due to the provision of other conditions, the process of caving has started. The mouth of the cave is located at an altitude of 1700 meters above the sea level, and the difference in height with the height of the spring that takes out the water from the cave's atmospheric fall and flows into the Shur River is 50 meters.The entrance of the cave is a 4,000-meter long corridor with a short roof and no stone cave and several sub-corridors. After the sub-corridor, there is a 950-meter wide corridor with 2-meter high uphills and dry pits, which continues with two 50-meter branches and then After crossing an uphill, you will reach a wide hall covered with drips, abstracts and columns. Inside the small crystal hall, which is attached to the hall of pillars, there is a well with a depth of 8 meters, which is probably the outlet of the waters that formed the cave.Currently, this cave is divided into three cultural, recreational and sports sections. Its sports section, which is only used by cavers and rock climbers, is about 4 kilometers, but its end has not yet been discovered. The recreational part of the cave, which is used for public visits, is about 2 kilometers of straight path, which is said to be only 1/3 of the entire cave. The cultural part of the cave is also located in its southern part. Its main part is a natural corridor that is used for holding various ceremonies. Of course, this corridor has no way out and its exit was artificially dug, but the corridor itself was completely natural.Katlekhor Cave is known as the first limestone cave in the world in terms of the quality of crystals and chandeliers, the beauty and the multiplicity of floors, which was ready for operation in five years by the investment of the private sector and the personal expense of the great engineer who was the civil engineer of Zanjan Governorate. About 15 years have passed since the initial exploitation of this cave, although exploration and activities are still ongoing to prepare other parts of the cave for visiting.Katlekhor Cave is a limestone cave where clay and soil containing iron oxide can be seen in some places. In terms of age, this cave is almost the same age as Ali Sadr Cave in Hamadan. Of course, these two caves are different in two ways; One is that the Ali Sadr Cave in Hamedan is a completely blue cave, while the Katlekhor Cave in Zanjan is an almost dry cave. Second, the limes of Katlekhor Cave are much purer than the limes of Ali Sadr Cave, which is a factor in making the cave more beautiful, because the purity of the limes makes them transparent and, as a result, light passes through the lanterns.An interesting point to note regarding the Katlekhor Cave is that the evidences and studies conducted confirm that this cave is ultimately connected to the Ali Sadr Cave in Hamadan. Also, one of the wonders and beauties of this cave is its multiple layers, which are rare in the world. It is believed that this cave has 7 floors, but only 3 floors have been discovered so far.The first 700 meters of the cave had a diameter of about 70 centimeters, so the early guides of the cave walked this 700 meters long and marked their path. The first 100 meters of the cave was inhabited by the first humans, which is confirmed by the skeletons of 80 people found in this place. It should be mentioned that these skeletons are still kept in this place. This cave has other parts, which can be listed as Sleeping Lion Square, Bistun Square, Chehlstun Square, Serahi Kohi, Panjshir Square, Bride Hall, Kandili Tunnel, Wedding Room, Elephant's Foot, Baghajaz Camel, Bride and Groom, Sham Square, Two Magicians, He mentioned the burnt palm, Maryam Magdas Square, etc.All these parts are the result of different limestone accumulations, each of which is called these names based on the similarity they have with one of the objects around us. One of the unique features of this cave is the presence of huge limestone columns, which are the result of the joining of stalactites and stalagmites, which have made this cave self-supporting, meaning that these huge columns play the role of supports that prevent the cave roof from collapsing. .In the early stages of its formation, this cave was a water cave, and due to water dissolution, sometimes huge masses of stones were separated from the main mass. The formation of multiple layers of this cave has caused water to penetrate into the lower layers and practically the cave has become a dry cave. Other prominent features of this cave include beautiful and transparent limestone stalactites and cauliflower stalactites.

The presence of very clear water springs around this cave and numerous natural holes are also unique features of this cave. In addition to all these issues, in Katlekhor cave, as mentioned before, you can see different gatherings, one of these beautiful and interesting gatherings is stalagmites that are very similar to the bride and groom and are named after them.

During the 120 million years of its existence, this cave has undergone many changes and transformations, some of which were natural and some were artificial. Among the natural changes of this cave, we can mention fractures resulting from earthquakes, faults, landslides and falls.