Lenzburg Castle () is a castle located above the old part of the town of Lenzburg in the Canton of Aargau, Switzerland. It ranks among the oldest and most important of Switzerland. The castle stands on the almost circular castle hill (altitude: 504 m), which rises approximately over the surrounding plain but is only about in diameter. The oldest parts of the castle date to the 11th century, when the Counts of Lenzburg built it as their seat. The castle, its historical museum and the castle hill with its Neolithic burial grounds are listed as heritage sites of national significance. History The prominent hill was already a settlement site in prehistoric times. For example, in 1959 a Neolithic gravesite was uncovered in the carpark. There have also been small discoveries from the Roman and Alemannic eras. A legend tells that there was once a dragon living in a cave in the hillside, who was defeated by two knights, Wolfram and Guntram. The grateful people made the two Counts of Lenzburg and gave them permission to build a castle on the hilltop. Seat of nobility A charter dated 1036 names one Ulrich, Count of Aargau. He was the Emperor's Vogt in Zürich and overseer of the abbeys of Beromünster and Schänis. The first definite record of the existence of a castle dates to 1077: Ulrich's grandson, also Ulrich, had taken the emperor's position in the Investiture Controversy and imprisoned two Papal legates for half a year. At that time the Counts of Lenzburg were among the most important feudal lords on the Swiss plateau and maintained close connections to the emperor. The line died out in 1173. Ulrich IV, the last Count of Lenzburg, named Emperor Friedrich I Barbarossa as his personal heir in his will; they had been on the Second Crusade together. The emperor came to Lenzburg Castle and personally supervised the division of the estate, giving a majority of the lands to his son, the Count palatine Otto of Burgundy. However, after Otto's death in 1200, the House of Hohenstaufen was forced to withdraw from the Aargau. By way of two neighbouring aristocratic houses (Andechs-Merania and Châlon), in about 1230 Lenzburg castle came by marriage into the possession of the Counts of Kyburg. They then founded a fortified market settlement at the western base of the castle hill, today's town of Lenzburg. Hartmann, the last Count of Kyburg,