Jews trace their origins in Lithuania back to the days of Grand Duke Gedeyminus, who founded the first Lithuanian state in the 14th century. By the late 15th century, there were already thriving communities. In time, Vilnius became known as the "Jerusalem of Lithuania," a great center of Jewish religious learning. The Jews of Lithuania lived an intense Jewish life, and their role and influence in the major Jewish political and cultural movements were far greater than their numbers would have suggested. There are synagogues in Vilnius and Kaunas, but attendance is low. Matzot and other supplies, such as kosher meat and wine, are imported. The Chabad House, with its own rabbi, has been especially active in organizing classes for young people and promoting knowledge of Judaism. On the eve of the Shoah, there were about 160,000 Jews in independent Lithuania and another 60,000 in Vilnius and the surrounding area, which were transferred to Lithuania after the Soviet conquest of eastern Poland. That population was bolstered by Jewish refugees from German-occupied Poland. During the German occupation, about 95% of Lithuanian Jewry was killed (a greater percentage than in any other community in Europe), in large measure due to the enthusiastic participation of ethnic Lithuanians. Important sites include the medieval Jewish quarter of Vilnius and the grave of the Vilna Gaon. The Romanesque-Moorish Choral Synagogue is the only Jewish house of worship to survive the Shoah. Among the objects in the State Jewish Museum in Vilnius are ritual items salvaged from the Great Synagogue that was destroyed by the Soviets. These include parts of the original ark and reader's desk. The museum also includes a section devoted to the destruction of Lithuanian Jewry. In Trokai there is a museum adjacent to the Karaite Synagogue that tells the story of this community. The Nazi killing grounds such as Paneriai (Ponary), where 70,000 Jews were massacred, and the infamous Ninth Fort of Kaunas also attract visitors.