In 1233 the knights of the Livonian Order captured the town. The army from Pskov Republic was sent to Izborsk. They freed the town, but in 1240 it was captured again. Only in 1242 the united army of Pskov Republic, led by Alexander Nevsky, defeated the German knights on Lake Chudskoye.
In the middle of the 14th century a stone fortress was erected in Izborsk by local builders and stonecutters fron Pskov. The remaining parts of those walls are now used as a basis of the present fortress. Together with the stone fortress the Cathedral of St. Nicholas was built.
Ancient Averter In the 15th century the fortress was reconstructed due to the development of fire arms. The walls were made higher and wider. Several new towers were added. One can observe the parts of the reconstruction even nowadays.
In the 16th century Pskov Republic joined the Moscow state and since then the fortress of Izborsk served to protect the borders of the state.
The decline of fortress began after the Northern War against Sweden when the borders of Russia were moved to the northwest. The fortress got the status of a provincial town in 1719.
From 1920 till 1940 Izborsk was the part of the independent Estonian state and had a name of Irboska. After the WWII it became a part of the Soviet Union and now it is a town of Pechorsky district in Pskov region.