Harhoog, Neolithic dolmen in Keitum, Germany

Harhoog is a rectangular megalithic tomb from the Neolithic period containing multiple stone burial chambers with parallel and transverse sections. The structure sits in Keitum on the island of Sylt and displays the typical building methods of this prehistoric burial culture.

The Harhoog was built around 3000 BC by the Funnelbeaker culture, whose settlements lay on Sylt; roughly 600 of the island's megalithic tombs once existed, about half survive. It was uncovered in 1925 during sand extraction for the Hindenburgdamm and archaeologically examined in 1936, after further sand removal for the Nössekoog dike. In June 1954 the chamber was moved to its present site because the ground was being removed for the expansion of Sylt Airport. Ernst Sprockhoff's atlas lists it as Sprockhoff 5.

The name Harhoog is not explained in the sources; the tomb is recorded as Sprockhoff 5 in Ernst Sprockhoff's atlas of German megalithic graves. It lies beside the Tipkenhoog, another mound near Keitum, and visitors reach it on foot from the village along the edge of the mudflats.

The monument stands outdoors and is accessible throughout the year, allowing visitors to examine the stone structure up close from different angles. The location in Keitum is easy to reach and provides good opportunities to study the construction from multiple viewpoints.

The Harhoog is listed as "Sprockhoff 5" in Ernst Sprockhoff's Atlas der Megalithgräber Deutschlands, which classifies it as an extended dolmen (erweiterter Dolmen) rather than a simple one. Its chamber has a rectangular enclosure with a half-height entrance stone, and the Tipkenhoog lies immediately beside it.