The Sun on The Floor of La Puerta del Sol in Madrid, Spain

Madrid was once a city with various walls protected from attackers. Gates were crucial to ensure movement in and out of the city which explains why Madrid is still today a city of gates.

Many of the gates once located around Madrid were demolished. Some still remain, while others have given their name to the place where they were once located. 

Puerta del Sol (Sun Gate) is actually a square and not a gate, but it owes its name to a long-gone gate that was decorated with a sun and was known to locals as "La Puerta del Sol."

There are two possibilities for the origin of the name Puerta del Sol for the square. One of them according to municipal records states that the square got its name from a sun-decorated medieval wall shutter that was destroyed in the 17th century. The other theory is that a gate was built with the sun's rising direction in mind—to the east.

The square has undergone many refurbishments, but this symbol remains as a nod to the past.