A deeply sobering place: at least 20,000 people were worked to death here building the tunnels beneath Mittelbau Dora, and the rockets now decaying within them, as part of Hitler's plans to wage war from underground. Visitors are free to roam the grounds, crematorium and museum, but you can only enter the massive tunnels by joining a free 90-minute guided tour: check the website for details. Allow enough time to get to the site, best reached by private vehicle.
The nearest station (tram 10 and Harzquerbahn from Nordhausen) is Nordhausen-Krimderode, from where it's a 20-minute walk.