Planegg is a municipality covering 10.63 square km in the District of Munich, in Bavaria. It is located on the river Würm, 13 km west of Munich and has a population of approximately 11,000. Although neighbouring communities were mentioned earlier, the first appearance of Planegg in written documents occurred in 1409. This document refers to the sale of Planegg to the Bavarian Duke, Wilhelm III, who between 1409 and 1423 also bought the villages of Großhadern, Martinsried, Forstenried, Fürstenried, Neuried et Gräfelfing. At this time Planegg became the stronghold of the Würm valley.
The castle of Planegg remains an important feature of the town. The original fortifications on the site were probably upgraded between 1415-1420 while the chapel of St. Magdalena was added in 1617. A copper engraving by Michael Wening done in about 1701 shows a complex construction with a characteristic onion dome. Further development, about 30 years later, expanded the castle and gave it its current Baroque appearance. The castle grounds, traversed by the Würm, were originally modelled on a French style park but were transformed around 1800 to the current the English landscape style.
At the end of the 19th century, due to its gentle climate and the clean waters of its river, Planegg attracted a large number of foreigners searching for a healthier lifestyle. The opening of the Pasing-Starnberg railway line in 1854 brought more residents of Munich into the town for rest and relaxation.
By 1930 the church at Martinsreid was inadequate to serve the growing population of the area and a new place of worship was built in Planegg. By the 1970s, the Max Planck Institutes for Biochemistry and for Psychiatry were based in the area and enjoyed international repute. This was reinforced by the three Nobel prizes won by scientists working in these institutes. Adolf Butenandt shared the prize for Chemistry in 1936 for his work on isolating sex hormones. Feodor Lynen, who gave his name to the secondary school in Planegg, shared his prize in Physiology and Medicine in 1964 for work on the metabolism of fatty acids while Robert Huber shared the Chemistry Prize in 1988 for his work on understanding the 3-dimensional structure of the reaction site in photosynthesis. Today the area of Martinsreid houses a number of research laboratories as well as department of the Ludwigs-Maximilian Science University of Munich.