Belém Tower is a UNESCO World Heritage Site that stands as an iconic symbol of the Age of Discovery.

The Spasskaya Tower, also known as the Savior Tower, is the main tower on the eastern wall of the Moscow Kremlin which overlooks the Red Square.

The Tower of Hercules is an ancient Roman lighthouse located on a peninsula about 2.4 kilometers from the center of A Coruña, Galicia, in north-western Spain.

The White Tower is a central tower, the old keep, at the Tower of London.

The Golden Gate of Vladimir, constructed between 1158 and 1164, is a rare and outstanding example of ancient Russian architecture.

The Flak Towers in Hamburg are massive, above-ground, anti-aircraft gun blockhouse towers constructed by Nazi Germany.

Fort Roughs is an offshore sea fort that was constructed during World War II.

The Flak Towers in Berlin are giant, anti-aircraft gun blockhouse towers constructed during World War II.

The Torres de Serranos is one of the twelve gates that formed part of the ancient city wall, the Christian Wall, of the city of Valencia, Spain.

The Kutafya Tower is a unique, outlying barbican tower of the Moscow Kremlin complex.