Burg, Medieval castle in Alzenau, Germany

Burg Alzenau is a late Gothic hilltop castle built 1395–1399 on a rock above Alzenau's market square. Its oval layout has a walled outer courtyard, once the economic yard, and an inner castle reached by a steep climb, with a 14 m high mantel wall on the northeast side. The palas has a stair turret and a round-arch frieze on corbels; below were servants' rooms, above a great hall and the upper knights' hall.

Burg Alzenau was built in the late Gothic style between 1395 and 1399 by the Archbishops of Mainz, during the tenure of Konrad II von Weinsberg and Johann II von Nassau, and served the Mainz electors as an administrative seat. From 1400 to 1500 it was repeatedly pledged to finance warfare. Swedish soldiers stormed the castle on New Year's Eve 1634; in 1816 it passed to Bavaria and became the seat of the Royal Bavarian district court.

The name Alzenau comes from the legend of "Allzunah": a lady of the Randenburg carried her husband to safety, saying "all too near" as she struggled. Since 1974–75 the restored Palas and courtyard have hosted the Burgfestspiele, AlzenauClassic and the Fränkische Musiktage.

The inner castle is reached only via a steep climb, and the Palas interior (fireplace, chapel oriel, kitchen and latrine oriels) can be visited only on group tours and during events. The outer courtyard and inner courtyard are used for events such as the Burgfestspiele and AlzenauClassic, so access may be restricted at those times.

The Palas hall is described in specialist literature as a "parade example of German castle architecture". Inside, a narrow spiral staircase leads to the upper Rittersaal, the lord's living quarters, which survives in late Gothic style with a fireplace, a small chapel oriel and kitchen and latrine oriels; it can be seen only on guided group tours and during events.