Nigeria?s rich and diverse artistic heritage goes back more than 2,000 years. The earliest noteworthy pieces are finely produced terra-cotta sculptures produced by the Nok culture in the vicinity of the Jos Plateau between 500 bc and ad 200. These, together with bronze heads from Ife dating from the 13th century and bronze plaques, bronze statues, and ivory carvings from Benin from the 11th century and later, are generally considered Nigeria?s most important artistic legacy. Many such pieces, however, reside in Western museums, where they were taken during the time of colonial conquest. The Nigerian government has demanded the return of looted art, particularly from Benin, with little success. Also important to Nigeria?s artistic heritage are wooden masks and fetishes (objects of worship or ceremony). Some of the finest examples are from cultures such as the Ijo, Ibibio, and Igala from southeastern Nigeria. Authentic examples of this art command high prices from collectors in the West, accounting for the frequent theft of ceremonial objects from shrines and museums in Nigeria. Modern artists typically draw on both African and Western influences. Members of the Oshogbo School, founded by Ulli Beier in the early 1960s, have explored Yoruba spirituality in several media. Leading Oshogbo artists include painter and musician Taiwo Olaniyi, also known as Twins Seven Seven; painter and writer Amos Tutuola; and sculptors Asiru Olatunde, Adebisi Akanji, and Susanne Wenger Alarpe. The development of modern Nigerian art has also been strongly influenced by students of the Zaria and Nsukka schools, dating respectively from the late 1950s and early 1970s. The Zaria school first explored the possibilities of synthesizing themes and techniques derived from both traditional and modern sources. The Nsukka school produces work that is known for its strong social and political content. Traditional architecture ranges from the North African-inspired mud houses of the Hausa to the sprawling Yoruba compounds that accommodate several branches of an extended family. Such dwellings are often decorated: Hausa houses commonly have bas-relief geometric designs, while Yoruba palaces feature elaborately carved doors and veranda posts. Older homes in Lagos have a distinctive two-story design, known as the Brazilian style because it was introduced by slaves repatriated from Latin America in the 19th century. The new capital city of Abuja, designed by members of the architecture school at Ahmadu Bello University, is the most outstanding example of contemporary Nigerian urban planning and architecture. The city?s governmental complex, cultural facilities, and main business district are grouped in a city center characterized by modern, futuristic buildings and wide boulevards, and residential districts extend outward from the core.