CaixaForum Barcelona

"The artwork here is almost secondary to its home: a 1911 former textile factory designed by Catalan architect Josep Puig i Cadafalch and inspired by medieval castles. The sprawling redbrick complex comprises several multilevel buildings featuring crenellated roofs, arches, and turrets connected by a series of courtyards. A modern white-stone, glass, and steel entrance was added in 2002, when the complex was renovated and turned into an exhibition space for the Caixa Foundation's extensive art collection. Climb the stairs to the roof terrace for the best view of this treasure's rich architectural details—not to mention the magnificent domed National Art Museum of Catalonia just across the way."