The German: Drei-Länder-Stein is a boundary stone at the tripoint of the German federal states of Lower Saxony, Saxony-Anhalt and Thuringia near the German: [[Großer Ehrenberg]]|italic=no mountain in the Harz.
The German: Drei-Länder-Stein is located in the South Harz at the tripoint of the three aforementioned states and also the tripoint of the counties of Goslar (Lower Saxony), Harz (Saxony-Anhalt) and Nordhausen (Thuringia). In addition the nature parks of Harz (Lower Saxony), Harz/Saxony-Anhalt and South Harz meet here. The boundary stone is around 3.3km (02.1miles) southeast of German: [[Hohegeiß]]|italic=no (Lower Saxony), some 3.3 km south-southwest of German: [[Benneckenstein]]|italic=no (Saxony-Anhalt), circa 1.8km (01.1miles) northwest of (Thuringia) and about 1.25km (00.78miles); all distances as the crow flies) northeast and below the summit of the German: Großer Ehrenberg|italic=no (; Thuringia) at about . The German: [[Bundesstraße 4]]|italic=no passes by just under 100 m southwest of the stone. There is a car park for hikers here called German: Jägerfleck.
The German: Drei-Länder-Stein was probably erected by 1749. It bears the inscription: HB (German: Herzogtum Braunschweig, 'Duchy of Brunswick'), AB (German: Amt Benneckenstein), which was later changed to KP (German: Königreich Preußen, 'Kingdom of Prussia'), and GW (German: Gräflich-Wernigeröder Forstgebiet, 'Comital Wernigerode Forest Estate').
During the Cold War (1945–1990) the stone became a boundary point along the Inner German Border, from 1945 between the British Zone of Occupation in the west and the Soviet Zone of Occupation in the east; and from 1949 between West and East Germany. The so-called Iron Curtain including the Convoy Way (German: Kolonnenweg) ran past this point. The Convoy Way used to act as a border patrol track, but is now a hiking trail.
Since 3 October 1990, German Unity Day, the boundary stone has marked the borders of Lower Saxony, Saxony-Anhalt and Thuringia. It is now part of the German Green Belt.
The German: Drei-Länder-Stein is no. 47 in the system of checkpoints in the German: [[Harzer Wandernadel]]|italic=no hiking system. The checkpoint box is located in a refuge hut some northeast of the boundary stones (ca. ; ). The Harz Border Way, a 75km (47miles) long hiking trail along the former Inner German Border, runs past the checkpoint.