The Hardenbergsches Haus offers a suitably prestigious setting for discussions, conferences and receptions. In the style of a state residence, the richness and variety of the furnishings and decor give the rooms a private and homely atmosphere.

The guest enters the house up a flight of steps into a large entrance hall, well suited to receptions, leading into the main ground floor space, the yellow room with damask-covered walls, comfortable club armchairs and sofas. In the adjacent dining room up to 32 people can eat or meet at the long table. From the first floor salon guests have a fine view across the Grosser Garten of Herrenhausen.

The library, installed in 2001, houses a comprehensive collection of books and illustrated volumes on the history of gardens. The vaulted cellar with its sandstone floors is presented as a simple and stylish wine cellar.

The connection with Baroque garden design is particularly strongly expressed in the 17th-century etchings adorning the walls. The newly-laid-out garden presents classical elements of modern garden architecture.