Neoclassical architecture developed between 1850-1900 as a reaction against Rococo ornamentation. It emphasized clean lines and drew inspiration from classical Greek and Roman architecture as well as the works of Andrea Palladio. Key characteristics included symmetrical designs, columns, and an emphasis on planar qualities over sculptural details. Neoclassical styles like Palladianism and the Adam Style spread across Europe and influenced early American architecture known as Federal style.