The eight-year-old NMAC Foundation, located on the southernmost tip of the Iberian Peninsula, invites contemporary international artists to Spain to complete site-specific projects. For the last two years NMAC has focused on an ambitious collaboration with Los Angeles-born artist James Turrell, legendary for his incredibly ambitious masterwork at Roden Crater, an extinct volcano in Arizona that he has been transforming into a celestial observatory for the past 30 years. Focused on perception, space and light, Turrell"s NMAC installation "Stupa," documented in this volume, is invisible from the outside. Viewers walk through a short "tunnel into a stone stupa--a dome-shaped mandalic structure found in Buddhist architecture, built to house relics. Turrell"s stupa frames the sky: as the light changes, the viewers" perception is tested, and light and structure blur until the light acquires an eerie tangibility and specificity.