Retz Stadt Haus Hauptplatz 02 und 34, Protected heritage building in Hauptplatz, Retz, Austria.

The Verderberhaus is a multi-part building complex at Hauptplatz 2 and 34 in Retz, crowned with crenellations. Its facade is designed in the Venetian Renaissance style, and the varying heights of the crenellated crowns offset the different levels of the three Gothic houses that preceded it.

The present building dates from the 16th century, when three Gothic houses were combined into one early modern townhouse; the middle one was recorded as the "Gewelibhaus" in 1437. The wings at numbers 2 and 34 are documented in 1532 and 1577, the eastern wing being the last part added to unify the house. Above the gate passage of the middle section an inscription names Hanns Fierenz von Goerz, 1583, rentmaster to Count Julius II of Hardegg.

The house is named after the "Verderber brothers" — Thomas Verderber (1792–1886) and Georg, Josef and Johann Verderber — merchants from the former German-speaking enclave of the Gottschee in the Duchy of Carniola, in present-day Slovenia, who moved to Retz in the early 19th century. Above the gate passage of the middle section, ornaments, lion figures and coats of arms accompany the inscription "Hanns Fierenz von Goerz, 1583"; Fierenz, a rent master of Count Julius II of Hardegg, had the house reshaped in the Venetian style, and his coat of arms carries the motto "Alles mit der Zeit".

The building sits at the center of the main square and is easily accessible on foot, though the interior is not open to public visits. From the street, visitors can freely observe and photograph the architecture and facade details at any time.

The two house numbers 2 and 34 mark where three Gothic houses were merged into one early modern building; the middle one was recorded as "Gewelibhaus" in 1437. The eastern wing, documented in 1577, received raised crenellations because its original pitched roof sat several metres lower than its neighbour's.