Konrad von Horneck donated his castle, which is situated on the river Neckar high above the town of Gundelsheim, to the Teutonic Order. He was the first commander of Horneck.
Horneck became the residence of the German Master for about one hundred years, and was thus the third most important seat of the Order after Marienburg/Malbork and Königsberg/Kaliningrad.
The castle was destroyed during the Peasant War. Götz von Berlichingen participated in its destruction.
A Renaissance building was errected on the site of the castle. It was later visited by the emperors Karl V. and Ferdinand II.
The castle was rebuilt in Baroque style.
Napoleon Bonaparte transfers the possession of the Teutonic Order to the Kingdom of Württemberg.
The castle was privatised.
Wilhelm Würth bought the castle. It became the Castle Brewery Hornegg.
The castle was refurbished in Art Nouveau style and became a sanatorium.
Dr. Ludwig Roemheld was the medical director of the sanatorium in the castle. One of the shareholders was the Heilbronn soup extract manufacturer Karl Knorr. High nobility such as Queen Charlotte of Württemberg, film stars such as Gustav Gründgens and Marianne Hoppe, mountaineer Luis Trenker and boxing world champion Max Schmeling were spa guests.
A TB sanatorium was set up in the castle.
Acquisition of Horneck Castle by the charitable organisation Johannes Honterus, founded by Transylvanian Saxons. A nursing home for the elderly was run here by the organisation until 2015. Rooms for the museum and library were also provided. The opportunity was taken to organise and expand their collections and develop them into the most important Transylvanian cultural institutions outside Romania: the Transylvanian Institute with Library and Archive and the Transylvanian Museum.
After the dissolution of the Johannes Honterus Association, an overwhelming fundraising campaign organised by the Transylvanian Saxons made it possible for the new charitable organisation Transylvanian Heritage and Community Centre Horneck Castle to purchase the castle, thus ensuring the continuation of the Transylvanian Museum and Institute.