Towards the Place Royale, the Hôtel Argenteau, the Hôtel Gresham and the Hôtel Altenloh were incorporated in turn in 1965, 1967 and 1969 respectively. An in-depth renovation of Balat's palace was carried out in successive stages from 1977. At the same time, in 1978, the construction of the underground part of the Museum of Modern Art began, with an entrance via the Hôtel Altenloh.
Towards the Place Royale, the Hôtel Argenteau, the Hôtel Gresham, and the Hôtel Altenloh were added in 1965, 1967, and 1969 respectively. An extensive renovation of Balat's palace was carried out in successive phases starting from 1977. Concurrently, in 1978, construction on the underground part of the Museum of Modern Art began, with an entrance through the Hôtel Altenloh.