Though just being an office building in downtown, the Metropolis Building has become an iconic landmark for Madrid, and probably the most photographed sight in the city. Originally topped with a Phoenix which the previous owner took with them, and replaced by the Metropolis company with an angel that seems to guard Madrid.
You can't miss this beautiful Beaux-Arts style building, which stands on the corner between Calle de Alcalá and Gran Vía. It's a great challenge for photographers to find the right angle and the right light, as the building is an amazing sight both day and night. Besides the Metropolis Building, the area surrounding it is full of great shots.
To see it from above, visit Círculo de Bellas Artes across the street. It's not free to get access to the terrace, but the view is worth paying for.