Bonngasse 23, Heritage monument in Bonn-Zentrum, Germany.

Bonngasse 23 is the surviving northern third of the former Gudenauer Hof, a U-shaped Electoral Cologne city palace whose facade once spanned today's Friedrichstrasse 35, Bonngasse 21 and 23. The L-shaped remnant keeps part of the courtyard wall, including an entrance portal converted into a window, with volute consoles and small flower calyxes probably carved in the first half of the 18th century.

The site is documented from 1481; in 1547 it passed to the Waldbott von Bassenheim family of Gudenau, and the name Gudenauer Hof is attested from 1625. From 1637 it was leased to the Cologne court marshal Johann Adolph Wolff Metternich. Probably destroyed in the 1689 bombardment of Bonn, it passed by inheritance in 1735 to the von der Vorst zu Lombeck family, who held it until 1812. The plot was divided in the 1860s, leaving only the northern third, and after changing owners in 2010 the ruinous house was restored in keeping with monument protection.

The name Gudenauer Hof has been documented since 1625, taken from Burg Gudenau, the ancestral seat of the Waldbott von Bassenheim family who bought the plot in 1547. The building faces the Beethoven-Haus across the Bonngasse, and the ground floor has served as a shop with display windows since the 19th-century subdivision.

The building sits in Bonn's heart and is easily reached on foot from the main train station or central bus stops. The surrounding area offers many restaurants, cafes, and shops nearby for a full walk through the center.

The courtyard wall preserves a former entrance portal that was later converted into a window; its volute consoles with small flower calyxes probably date from the first half of the 18th century. The building stands directly opposite the Beethoven-Haus.