Magnificent skyscrapers and steel-and-glass buildings tower over the city, standing guard to one of Europe's largest financial centers. Nicknamed 'Mainhattan' for its businesslike personality and commercial spirit, Frankfurt Am Main appears different from the rest of the German cities. One of the world's largest stock exchanges calls this city home, as do a warren of national banks and financial institutions. Besides its modern architecture, it also features traditional architectural examples across the city. There is a host of 20th-century architecture that dots its streets, including timeless landmarks like the Goethe Haus, the post-war Bayer Haus and the Frauenfriedenskirche. Römerberg, Frankfurt's nostalgic plaza in Old Town, houses a beautiful set of half-timbered houses and 19th-century churches that contrast the city's modernity. Other landmarks like the famous Alte Oper remind about the city's cultural interests.