A fortress situated southwest of the city of Pskov in Russia.
The first fortified settlement at Izborsk was founded at the end of the eighth century on high ground with steep slopes by the confluence of a small river with Lake Gorodishchenskoye; it was linked by a system of watercourses to Lake Pskovskoye. A stone fortress was built in the second half of the eleventh century when Izborsk became the main outpost on the western frontier of the Novgoro- dian state. Thereafter it was considered by the crusading orders of Livonia as the key to the city of Pskov, and was frequently subject to attack by them.
In 1233 the troops of the vassals of the bishopric of Dor- pat and their ally Prince Yaroslav of Pskov, who was attempting to restore his rights to the Pskov principality, captured the fortress, but they soon retreated after troops from Pskov came to its relief. In September 1240 Izborsk was occupied by the Teutonic Knights from Livonia and their allies after a week-long siege and was freed only in March 1242; it was burned down by the Livonians before the siege of Pskov in May 1269. In 1330 a new fortress was built on higher ground to the south, and from that time it was practically unassailable, withstanding several sieges by the Livonians, notably in 1341 and in 1348.