Ilsenburg (German: [ˈɪlzn̩ˌbʊʁk] ) is a town in the district of Harz, in Saxony-Anhalt in Germany. It is situated under the north foot of the Harz Mountains, at the entrance to the Ilse valley with its little river, the Ilse, a tributary of the Oker, about six 6 miles (9.7 km) north-west of the town of Wernigerode. It received town privileges in 1959. Owing to its surrounding of forests and mountains as well as its position on the edge of the Harz National Park, Ilsenburg is a popular tourist resort. Since 2002, it is officially an air spa.

The old castle, Schloss Ilsenburg, lying on a high crag above the town, was originally an imperial stronghold and probably built by King Henry I. In 995 Emperor Otto III resided in Elysynaburg, which Henry II bestowed in 1003 upon the Bishop of Halberstadt, who converted it into a Benedictine monastery. The school attached to it enjoyed a great reputation towards the end of the 11th century. The abbey was finally devastated during the German Peasants' War in 1525.

After the Reformation the castle passed to the counts of Wernigerode, who restored it and made it their residence until 1710. Higher still, on the edge of the plateau rises the Ilsenstein, a granite peak standing about 500 ft (150 m) above the valley, crowned by an iron cross erected by Count Anton von Stolberg-Wernigerode in memory of his friends who fell in the Napoleonic Wars of 1813-1815. Numerous legends cluster around this rock.

Ilsenburg is between Wernigerode (Saxony-Anhalt) in the east and Bad Harzburg (Lower Saxony) in the west through the Ilsetal. The Brocken is reachable through the Heinrich-Heine-Weg, that goes along the Scharfenstein and Kleiner Brocken. Ilsenburg is near the Harz National Park. To the west, there is the Harzer Grenzweg at the Green Belt Germany, which goes along the inner German border.

The town Ilsenburg consists of Ilsenburg proper and the Ortschaften (municipal divisions) Darlingerode and Drübeck. Darlingerode and Drübeck were independent municipalities until they were absorbed by Ilsenburg in July 2009. Other localities within the town are Plessenburg (part of Ilsenburg proper) and Oehrenfeld (part of Drübeck).

• Am Kruzifix
• Ilsenburg Abbey
• Ilsenburg House
• Ilse valley and Princess Ilse
• Ilsestein
• Froschfelsen
• Market place and chemist's
• Krug Bridge over the Ilse
• former Ilsenburg Factory, today used as a residence
• Bremen Hut, a checkpoint on the Harzer Wandernadel and refuge hut in the Ilse valley

Ilsenburg has access to the Bundesstraße 6 federal highway leading from Goslar and the Bundesautobahn 395 to Halle and the Bundesautobahn 14.

At the Ilsenburg train station rail transport is available to Vienenburg and Hanover as well as to Halle and Berlin by Regional-Express trains of the Deutsche Bahn and trains of Veolia.

• Bad Harzburg, Germany

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Ilsenburg". Encyclopædia Britannica. Vol. 14 (11th ed.). Cambridge University Press. p. 328.

• Official site
• Ilsenburg Abbey Archived 2016-03-19 at the Wayback Machine