American style
Plaza de Callao or Callao Square is one of the most central and busiest squares in the entire city of Madrid since it is crossed by Gran Vía. Personally, it is one of my favorite squares in the capital, since the buildings have a great personality and are influenced by American architecture, more precisely Chicago and New York. A good example is the Cinema Building Callao, of 1929, copying the style of the American school of Chicago.
One of my favorite buildings in Madrid is on this square, the Capitol building, better known as the "Schweppes Logo" building, since it has on its facade a huge neon with the drink brand, which also appears in some Spanish movies scenes like the famous "El Día de la Bestia".