The Osun-Osogbo grove is a living Yoruba sanctuary, a UNESCO World Heritage site, and substantially a twentieth-century artwork, and the priesthood that runs it says so.
The compact. Osogbo's founding tradition is an agreement: the town was permitted on the river on condition that the grove was protected and Osun honoured. That bargain is renewed publicly every year at the festival, which makes the grove a contractual obligation rather than a monument.
The decay. By the 1950s much of the forest had been encroached on by farming and logging, shrines had fallen down, and the priesthood was ageing in a town where conversion to Christianity and Islam was steady. The grove was being lost by neglect rather than by any single act.
Wenger. Susanne Wenger (1915-2009) was an Austrian artist who came to Nigeria in 1950. She was initiated into the Osun priesthood, took the name Adunni Olorisha, settled permanently in Osogbo, and over four decades worked with local artists, among them Adebisi Akanji and Buraimoh Gbadamosi, to rebuild the shrines. What they made is not restoration. It is a body of large, strange, organic sculpture in mud and cement, unlike anything in earlier Yoruba art, made by initiates as devotional work.
The honest complication. A visitor walking the grove is largely looking at sculpture made after 1960. This is stated openly by the priesthood and in the site's own documentation rather than smoothed over, and it produces a genuinely interesting question that the site answers in practice rather than in theory: is a sacred place authentic because it is old, or because the obligation attaching to it is still being met? Osogbo's answer is the second. The shrines are new; the orisha, the priesthood, the festival and the compact are continuous.
The festival is the point. Each August the Osun festival runs for two weeks and closes with the Arugba, a votary maiden of the royal house, carrying the sacrifice on her head from the palace through the town to the river, with the crowd following and forbidden to let her stumble. It draws people from across Nigeria and from Yoruba-descended communities in Brazil, Cuba and the United States, many of whom are practitioners of Candomble or Lucumi returning to a source rather than tourists observing one.
Inscribed by UNESCO in 2005, at Nigeria's nomination, on the basis that it is the last such grove of any size and that it remains in active religious use. Both halves of that were true because of Wenger's work and are sustained now by the priesthood.