Tatların underground city was discovered only in 1975 because its original entrance had collapsed and it took many years before it could be opened to public in 1991. It is believed to have been an important centre for either religious or military purposes, judging by the large size of its rooms and the fact that there is a church with well-preserved frescoes right next to it. Currently only four floors of the underground city, which is spread over a pretty large area, can be visited but work continues to open more floors to to public.
The entrance to Tatların underground is through a 15 meters long passageway that opens to a relatively large hall. There is a millstone door, which could only be opened from the inside, had the purpose of sealing off the entrance in the event of an enemy attack. Three skeletons were found in the section leading downwards from the right side of the hall. The kitchen found on the right side of the hall provokes the idea that this section was used as a burial ground in the Roman period and as a kitchen in the Byzantine period, because the burial places in which the skeletons were found are identical with those used in the Roman period. However, the interior parts of the burial places were later deeply carved out so as to put food supplies in them.
The large hall at the entrance is connected to another large area with a zigzagging corridor. There is a trap and a millstone door against intruders. There is also a stable and five food supply storages carved into the floor in this second section which is supported by strong columns. In the ceiling there is a ventilation shaft which provides access to the other parts of the settlement. Two Roman toilets were found in the settlement which shows that toilets were used in Anatolia already about 3000 years ago.