As early as 1600 the Teutonic Order (Deutscher Orden) had the palace fortifications of its Mergentheim residence expanded and a garden laid out. In the second half of the 18th century the southern section of the palace was extended with an orangery and "Sala terrena" - a pavilion in the form of a garden hall with a small, symmetrical garden before it.
In the late 18th and early 19th century, the last Grand Master (Hochmeister) had the palace garden converted to an English landscape garden, which corresponded to the taste of that age. The Little Half-Moon House (Halbmondhäuschen) and the Little Bell House (Schellenhäuschen), a Turkish and a Chinese pavilion, have been preserved until today. The lake and the Rousseau island were reconstructed in the late 20th century.