Horta, Victor, Baron, 1861–1947, Belgian architect. The Tassel House in Brussels (1892–93), his first mature work, was the earliest monument of art nouveau. It was excelled only by his later works, such as the Baron von Eetvelde house (1895) and the demolished Maison du Peuple (1896–99), both in Brussels. The houses are especially significant for their interior architecture. The irregularly shaped rooms open freely onto one another at different levels. The plantlike design of the iron balustrade is echoed in the curving decorative lines of the mosaic floors, plaster walls, and other surfaces. Horta later reverted to a more traditional mode of architectural expression.