A form of textile arts, tapestry making involves the often-meticulous process of weaving continuous and discontinuous threads of fabric to produce either pictorial or abstract designs. While the earliest tapestries date to 11th-century Germany, in several European centers the commercial production of tapestries for nobility began in the 14th century and expanded thereafter. Among the most iconic works produced during this period are the seven tapestries of The Hunt of the Unicorn, which are made of wool, silk, and metallic thread and follow a detailed, symbol-laden narrative. With changing tastes and attitudes in Europe, commercial tapestry production substantially decreased in the 19th century. Interest in tapestry was renewed in the late 19th century by the Arts and Crafts movement in England and the Wiener Werkstätte in Germany, which advocated preindustrial craftsmanship. In the 20th century, artist Anni Albers was a proponent of tapestry weaving at the Bauhaus and at Black Mountain College, while present-day artists such as Sheila Hicks continue in this tradition. Alighiero e Boetti is known for involving other craftsmen in the production of tapestries, while El Anatsui incorporates scrap metal and discarded plastic into his intricate tapestry-like wall hangings.