The floor plan of the castle still conveys in its purest form the construction idea on which the Staufer castle was based. In the marshy valley of the Seemenbach, a mighty defensive wall was erected on an oak pile grating, enclosing the Romanesque core castle in a thirteenagon shape.

Ihe the inner area, the buildings lean against the defensive walls, while the outer facade was designed with defensive humpback cuboids. The construction of the moated castle, the main parts of which have been preserved, was probably undertaken by Hartmann von Büdingen in the second half of the 12th century.

The probably younger outer bailey adjoins to the west. It also had a defensive function, but also served as a farmyard. The watchtower on the south side replaced an older gate in the 16th century. Opposite is the New Building, a simple functional building from the 19th century. The outer courtyard receives its special flair from a magnificent group of trees.

"Wild men" stone coat of arms holders, around which many stories are told, guard a gateway with two pointed arched openings, above which the rollers of a drawbridge can be seen. The coat of arms decoration on the star vault inside dates back to the late 15th century. Behind concealed is the old gate of the Hohenstaufen castle, which shows the Ysenburg coat of arms as well as a small lion shield, presumably the official coat of arms of the Lords of Büdingen.

The hall-shaped entrance with old fire extinguisher buckets on peg boards leads to the inner castle courtyard. The various epochs and styles merge here to form an atmospheric whole. The quiet splashing of the old fountain or the former dovecote contribute to the unique magic of the courtyard ensemble.

The Romanesque Pallas dominates the north side with its clearly structured front. A high-quality remnant of the adjoining castle chapel to the east has been preserved in the gate and tympanum with two kneeling figures in front of a cross, perhaps a reminder of two Büdingen lords who never returned from the crusade in 1196.

An ogival tracery window gives an idea of the Gothic chapel; above it the so-called high school was added in the 16th century. Gothic buildings follow; the hall building and the kitchen building, with more recent oriel windows decorated with coats of arms.

Remarkable is a sandstone plaque with the Ysenburg-Nassau alliance coat of arms and a shawl as a coat of arms holder, for contemporaries probably a symbol of court and residence character. Stair towers from the end of the 15th and 16th centuries, Renaissance-style gables from the 1600s and a portal designed in 1673 in the peculiar "cartilage baroque" style round off the architecture.