Boo Castle (Boo slott) was built between 1878 and 1882 by the then tenant in tail of the Boo estate, Hugo Johan Hamilton, and his wife Marianne Hamilton (born af Sandeberg). The castle was constructed in so-called neo-Gothic style, according to a design by Johan Fredrik Åbom. It was built in stone with towers, crenellated walls and crow-stepped gables.
Between 1925-1927 the interior was reconstructed and renovated by the architect Ivar Tengbom. Simultaneously, the landscape architect Rudolf Abelin designed a new landscape park in English style around the castle.
In 1959, the castle was re-painted in a pinkish colour with white window frames. This was probably done in accordance with the original design drawings from 1875. In these the castle was decorated in a bright red brick hue. However, the castle was originally painted white with dark woodwork, and equipped with sun blinds on the south side.
The present colour scheme was applied in 2008-2010, when extensive restoration and renovation works of the castle were carried out.