After the death of Prince Giovanni Torlonia (1938) the House of Owls began to decay, occupied, as all of the park was, by the Anglo-american troops from 1944 to 1947.
In 1992 the restoration works, which had been planned for a while, began.
The reconstruction made use of photographs from various periods (some from the 30s, others from 1978), numerous archive documents and verbal records made in 1944 and 1947, the points at which the Anglo-american troops requisitioned and reconsigned the buildings.
The photographs were used to reconstruct the exterior view of the building, while the verbal accounts and archive documents gave useful information about the decoration and the interior furnishings.
At the beginning of the restoration all the fragile decorative elements, such as the glass, the wooden panelling, the majolica, and the built in furnishings were, as far as possible, removed into storage, and underwent separate restoration before they were returned to their places.
All the immovable decorations, such as the stucco and the tempera painting, were then secured, before work proceeded to the restoration of the architectural structure.
All the pre-existing elements have been restored and replaced, with the exception of the roofing, dressed with asbestos, a material which the regulations now forbid. It has been replaced with slate tiles, as in the original construction. The cleaning of the many doors and windows was extremely labour intensive: they were removed, restored and catalogued and, where possible, replaced in position, or reconstructed on the basis of the original modela.
The restoration was completed in 1997.