It is embellished with many Renaissance decorations based on Italian models taken from Sebastian Serlia's books.

When initially opened, the lobby and guest rooms showed "a rather free interpretation of Spanish Renaissance decoration."

To the north, it was fortified in a medieval style, but the southern face had ornate Renaissance decoration, with tall octagonal towers at each end.

The cast bronze sides are covered with Renaissance foliate decoration.

Michael Bath, Renaissance decoration in Scotland, NMS, (2003), ISBN 1-901663-60-4.

The Guard Room, the former great hall of the fortress (now known as the State Hall), was transformed by new Renaissance decorations and the addition of a monumental chimneypiece.

The main building is flanked by two round towers and the architectural style blends traditional mediaeval sturdy design with more elegant Renaissance decoration.

The well with Renaissance decoration, the main door with pilasters and the staircase turret date from the 16th century.

The Renaissance decoration continued inside, although little has survived the building's military use, excepting the carved stone fireplaces.

The Library, now the President's office, and the Dining room, both on the south side of the Great Hall, contain many elements reminiscent of French Renaissance decoration.