Castle Solitude in Germany was built as a hunting lodge between 1764 and 1769 under Duke Karl Eugen of Württemberg. It is not a true castle, but rather a rococo palace. Since 1956 the area has belonged to the urban district of Stuttgart, Germany. The castle lies on a long-drawn-out plain between the cities of Leonberg, Gerlingen and Stuttgart. The castle offers views to the north.
The construction period of the castle was characterized by political and financial difficulties. Karl Eugen had taken Württemburg into the Seven Years' War on the losing side against Prussia. Financially, the building exceeded the financial burden that the duchy of Württemberg could handle. In addition to the financial problems of the state, political conflicts of the duke with the influential Stuttgart land barons led to the Duke shifting his temporary residence from Stuttgart to Ludwigsburg. In the long run, the castle was prohibitively expensive to keep as just a residence. In 1770 a high school was created by Duke Eugen. In 1775, the high school was moved to Castle Solitude. It served as an academy of arts and as a military academy, and later still as a general university for the children of the elite. Eventually, the costs of maintaining the castle kept it empty after it was abandoned as a school after the Duke's death late in the 18th century. Between 1972 and 1983 the Federal Republic of Germany restored the castle.
Since 1903 the Castle Solitude was the finishing point of hillclimb races. In later years, the grounds of the castle served as driver camps, especially for closed-circuit races with different fastidious track variants in the hilly area, reminding of the Targa Florio. From 1935-1965, the 11.3 kilometers course south of the castle was used for World Championship motorcycle Grand Prix racing. From 1961 to 1965, a series of non-campionship Formula 1 races were held also at the same weekend. Pilots were, among others, John Surtees, Jim Clark, Dan Gurney, Jack Brabham. The Solitude races attracted crowds of 288,000 spectators per event in average, but were discontinued after 1966.
In 2003, a revival-competition in and around the castle-grounds took place, with former competitors and even world-champions like Giacomo Agostini being present, driving their famous machinery. A rally to commemorate the 50th birthday was held in 2004.