The Romanesque castle on Burgplatz was Henry the Lion's palace and the seat of ducal power for the Welf dynasty in the 12th century. The building standing today is a careful 19th-century reconstruction on the original footprint, with the great hall — the Rittersaal — restored to something approaching its medieval grandeur.
The castle houses part of the Braunschweigisches Landesmuseum collection, including the original Henry the Lion bronze lion (1166) — one of the earliest monumental bronzes cast in medieval Europe — displayed under protective cover in the great hall. The replica outside on the pedestal is from 1858. The juxtaposition of the two, seen together, makes plain what 700 years of outdoor exposure does to bronze.