The town lies in the Westerwald between Koblenz and Siegen, roughly 10 km west of Bad Marienberg on the river Nister.

Building was finished in 1212 under Count Heinrich III, the founder's son, who was also mentioned as the town's and the castle's first owner.

The Romanesque St. Bartolomäuskirche, built there about 1200 and nowadays an Evangelical church is Hachenburg's oldest preserved building, followed by the Steinernes Haus (“Stone House”), known as Zur Krone, from the 15th century, at the Old Market (Alter Markt) in the town centre.

Most of the lovely timber-frame houses on Friedrichstraße, Herrnstraße, the Old Market, Perlgasse, Mittelstraße, Judengasse and Wilhelmstraße come from the 17th and 18th centuries.

In the Second World War, Hachenburg was largely spared any great damage, but other disasters had ravaged it in the past.

Most of the still preserved graves were made by Hachenburg stonemason and sculptor Wilhelm Sax (16 August 1891 – 26 June 1955).