 Some were relatively conservative buildings in a classical style, such as the Mutual Life, Atlantic Mutual, and Broad Exchange Buildings, all designed by Clinton and Russell.Others broke new ground, including the Flatiron Building which opened in 1903 near Madison Square.The Chicago firm of Daniel Hudsdon Burnham designed the high, 21 story structure; the unusually shaped, narrow building needed particularly strong wind bracing, while the facade was richly textured and incorporated stylistic features more common in Chicago.