One of the main attractions of Izborsk is the fortress on Mount Zheravya, built in the 14th century and preserved to this day in relatively good condition. It is believed that the history of Izborsk began with this fortress, which long protected the western borders of the country.

The original fortress looked different from today. It had two gates: one led to the settlement, the other to the lake with a pier. The height of the walls reached 3 meters, while the earthen rampart was 6 meters high. The second fortress was initially wooden, and only the "Lukovka" by the eastern wall was made of stone. This round tower, with a diameter of less than 10 meters, rose to 12 meters. Next to it was an underground passage over 16 meters deep, which led from the fortress to the lakeshore. Later, during the reconstruction of the fortress in stone, the walls were made double and surrounded by a moat, and then the remaining towers were built to accommodate artillery. For the convenience of the artillerymen, the towers were extended forward from the level of the walls. All of them were round in shape, except for the five-tiered rectangular "Ploskushka."

The stone walls of the Izborsk fortress reach 3 meters in thickness, and their total length is about 850 meters. Unfortunately, of all the towers, only "Lukovka" has preserved something impressive, while the others are empty and devoid of interior decoration.

In the mid-19th century, Nicholas I ordered the walls to be repaired and a new bell tower to be installed, but later the fortress remained unattended for a long time. The restoration project began in the 1960s and resumed in 2010. Currently, the fortress has been partially reconstructed: the "Lukovka" tower has been renovated, and an observation deck has been arranged on it. In total, the fortress has seven towers with charming names such as "Ploskushka" and "Ryabinovka." The total area of the fortress is about 2.5 hectares.