Spanish architecture has a long and varied history, from ancient burial chambers built in 4000BC to modern works. Notable periods include Roman architecture which introduced civil engineering like aqueducts and roads, Gothic cathedrals built in the 12th-13th centuries, Renaissance palaces in the 15th-16th centuries like El Escorial, and Barcelona's iconic buildings by Gaudi in the 20th century Catalan Modernism style. Spain has a wealth of architectural styles and UNESCO World Heritage Sites that showcase its rich architectural history.