The Grand Castle Ansembourg, located in the valley of the Eisch in central Luxembourg, is one of the castles belonging to the Valley of the Seven Castles. Built from the first half of the seventeenth century as "House Forges" by Thomas Bidart, a metallurgist from Belgium, the castle experienced a significant transformation in the eighteenth century, when his heirs found themselves elevated to Baron (1728) and Earl of Marchant and Ansembourg and Count of the Holy Roman Empire (1749-1750). The gardens were laid out in 1750 and are adorned with statues, stairs and decorative fountains.
In 1639, Thomas Bidart built the central part of today's castle as a house surrounded by walls and towers, two of which still stand. Bidart, who was a pioneer of Luxembourg's iron and steel industry, named the building Maison des Forges (House of the Ironworks). During the Thirty Years' War, he tapped the region's many water sources and exploited its timber and iron. As a result, his family prospered, earning rights to the title of Lords of Amsembourg.
Thomas Bidart died in 1670 and his daughter, Marie-Anne Bidart inherited the forges. She married François de Thomassin. In 1678, she erected the chapel of "Mont Marie", endowed with a charitable foundation for the education of poor children in the region, on the slope of the overhanging hill, connecting them with the castle by a staircase and a path.
It was the de Marchant family who, after inheriting the property by marriage, undertook its astonishing transformation into today's modern-looking castle. In 1719, the courtyard was extended with two wings on either side of the original building. The southern gable was enhanced with a magnificent arch where four statues represent four continents. Fitted with two small towers, the new façade overlooked the gardens which were connected to the castle through an arcade. The first-floor balcony above the porch provided a view of the gardens, complete with flowerbeds and a fountain. The year of the transformation is mentioned on the facade, above the arches.
Between 1740 and 1750, Lambert Joseph de Marchant et d'Ansembourg continued to beautify the castle, further improved the gardens and extended the buildings on the north side of the main courtyard. In 1759, the Count added the impressive Baroque gateway bearing the arms of de Marchant of Ansembourg and Velbruck.
In the early 1970s the castle hosted a foreign studies program for students from three American private Catholic Colleges. Students lived in the newly created dorms on the second floor, and took classes in Literature, Art History, Music Education, and Foreign Language. They also assisted with art restoration and teaching music at DuPont International School. One of the partner colleges, Mercy College of Detroit, sent professors. Since 1987, the castle has belonged to the Japanese organization which uses the castle as its European and Africa headquarters and holds ceremonies and seminars throughout the year for its members. The organization has undertaken substantial renovation work with the assistance of Luxembourg's Service des Sites et Monuments nationaux. Initially work was centered on reinforcing the foundations and walls and on restoring the staircase of honor on the upper terrace in the gardens. From 1999, the statues and the fountains in the garden were repaired while the roofs over the two wings and the central section were rebuilt. The castle also hosts a number of cultural events during the year.