"Dornburg" in etymological sense is compound by dorn (thorn ) and burg (castle). In Germany there are 3 places with the name "Dornburg": 1. Community in Westerwald in County of Limburg-Weilburg in Hessen with a roughly 396-m-high elevation upon which are found the remains of a ringwall site from La Tène times (5th to 1st century BC). Within it lay a Celtic settlement rather like a town. (Coordinates: 50°30′13″N 08°01′28″E); https://en.wikipedia.org/wiki/Dornburg,_Hesse
2. Dornburg is a town in the Saale-Holzland district, in Thuringia. It sits atop a small hill of 400 ft above the Saale river. Dornburg is mainly known for its three grand ducal castles, once belonging to the former grand-dukes of Saxe-Weimar-Eisenach. These are:
[1] Altes Schloss, which is built on the site of older castles from the early 12th century. One such castle was the Kaiserpfalz, often a residence of the emperors Otto II and Otto III, and where the emperor Henry II held a diet in 1005. [2] Neues Schloss or "Rokokoschloss", built in the Italian style in the years 1728–1748. It features pretty gardens that drew the likes of Goethe. [3] The third and southernmost of the three is the so-called Renaissanceschloss, which was built in the 17th century on the site of an older castle. Coordinates: 51°0′23″N 11°39′58″E; One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Dornburg". Encyclopædia Britannica. 8 (11th ed.). Cambridge University Press. p. 430; https://en.wikipedia.org/wiki/Dornburg
3. Castle of the parents of Catherine the Great from Russia, prev. princess Sophie Auguste Friederike of Anhalt-Zerbst. Coordinates: 52° 2′ N, 11° 53′ E; https://de.wikipedia.org/wiki/Dornburg_(Gommern)