The Arenberg site had been the castle of the lords of Heverlee since the 12th century, but this family became impoverished and had to sell the site in 1445 to the Croÿ family from Picardy. Antoon van Croy demolished the medieval castle and started works to build the current château in 1455 on the site, of which he destroyed all but one tower. Willem van Croÿ completed the works on the château in 1515, and founded a monastery on the château grounds for the Benedictine Celestines. The architectural style is in large part traditionally Flemish, with sandstone window frames and brick walls, though it has been structurally altered since 1515 and has elements of Gothic, Renaissance and Neo Gothic architecture. Its large corner towers are typical, once surmounted by a German eagle.
Charles III of Croy was the 4th and last duke, and after his death in 1612 without issue the château passed to the Arenberg family into which his sister had married, and remained in that family until the First World War.
During the First World War, the château and grounds were occupied by the Germans and Austrians. The château and park were seized by the Belgian government on the outbreak of, and then after the war since the Arenberg family was considered to be German or Austrian due to their close Habsburg connection, monarchs of Austria-Hungary. It took until 1921 for the University to acquire them, becoming an expanded natural sciences and engineering campus in the style of that of an American university. After the partitioning of the university along language lines in 1968, the château and grounds remained with the Dutch speaking half as one of the main campuses for the new, independent Katholieke Universiteit Leuven. The château itself is the main building of the Faculty of Engineering and houses lecture rooms and studios for the Department of Architecture, Urbanism and Urban Planning, including the Post-Graduate Centre Human Settlements and the Raymond Lemaire International Centre for Conservation. The building is open to the public. The former Celestine monastery on the château grounds now houses the campus library, and the addresses of many of the science buildings are on the street named Celestijnenlaan (Dutch for 'Celestine Street').References:
The famous Italian Medici family have given two queens to France: Catherine, the spouse of Henry II, and Marie, widow of Henry IV, who built the current Luxembourg palace. Maria di Medici had never been happy at the Louvre, still semi-medieval, where the fickle king, did not hesitate to receive his mistresses. The death of Henry IV, assassinated in 1610, left the way open for Marie's project. When she became regent, she was able to give special attention to the construction of an imposing modern residence that would be reminiscent of the Palazzo Pitti and the Boboli Gardens in Florence, where she grew up. The development of the 25-hectare park, which was to serve as a jewel-case for the palace, began immediately.
The architect, Salomon de Brosse, began the work in 1615. Only 16 years later was the palace was completed. Palace of Luxembourg affords a transition between the Renaissance and the Classical period.
In 1750, the Director of the King's Buildings installed in the wing the first public art-gallery in France, in which French and foreign canvases of the royal collections are shown. The Count of Provence and future Louis XVIII, who was living in Petit Luxembourg, had this gallery closed in 1780: leaving to emigrate, he fled from the palace in June 1791.
During the French Revolution the palace was first abandoned and then moved as a national prison. After that it was the seat of the French Directory, and in 1799, the home of the Sénat conservateur and the first residence of Napoleon Bonaparte, as First Consul of the French Republic. The old apartments of Maria di Medici were altered. The floor, which the 80 senators only occupied in 1804, was built in the middle of the present Conference Hall.
Beginning in 1835 the architect Alphonse de Gisors added a new garden wing parallel to the old corps de logis, replicating the look of the original 17th-century facade so precisely that it is difficult to distinguish at first glance the old from the new. The new senate chamber was located in what would have been the courtyard area in-between.
The new wing included a library (bibliothèque) with a cycle of paintings (1845–1847) by Eugène Delacroix. In the 1850s, at the request of Emperor Napoleon III, Gisors created the highly decorated Salle des Conférences, which influenced the nature of subsequent official interiors of the Second Empire, including those of the Palais Garnier.
During the German occupation of Paris (1940–1944), Hermann Göring took over the palace as the headquarters of the Luftwaffe in France, taking for himself a sumptuous suite of rooms to accommodate his visits to the French capital. Since 1958 the Luxembourg palace has been the seat of the French Senate of the Fifth Republic.