Villa Borgnis, Spa house in Königstein im Taunus, Germany.

Villa Borgnis is the Kurhaus of Königstein im Taunus, built in 1860 in the Black Forest style at Hauptstraße 21. The core is the former Gasthaus am Grünen Baum, extended with an annex in 1870 and a veranda in 1878. It now houses a restaurant, a wine tavern and the town's registry office.

Originally operating as a guesthouse called am Grünen Baum, the property was purchased in 1838 by banker Matthias Franz Borgnis who transformed it into a villa. In August 1927 it reopened as a public spa house after the town had pursued this goal for more than 76 years.

The house became the centre of public life in Königstein after 1927, hosting events of many kinds; in 1947 the Junge Union Deutschlands was founded here. From 1976 to 1997 it also housed the town library. Today the registry office of Königstein im Taunus is based in the building, and a restaurant, café and wine tavern occupy the ground floor.

The building stands at Hauptstraße 21, with the Kurpark behind it. It closed for a full renovation from 1997 and reopened on 1 May 1999. The restaurant, café and wine tavern serve visitors, and the town's registry office is housed inside, so civil ceremonies take place here.

The first tenant to run the restaurant was Fritz Ehrlicher, who had previously managed the Kurhaus in Bad Soden am Taunus. From 1976 to 1997 the villa also housed Königstein's town library, before a full renovation closed it from 1997 until its reopening on 1 May 1999.