Madrid is thick with fountains. This one is one of the two lovely ones here on Paseo del Prado, the other is the Neptune. It sits in the center of a roundabout, with bus stops at one end (one of which will take you to the airport).
Cibeles is the mother goddess, identified in the Greek panthoen with Rea, the mother of the Olympic gods and is the symbol of the earth and fertility. In the fountain, she sits on a chariot pulled by the lions Atalanta and Hipómenes. She caries a scepter and a key.
Considering that it was built between 1777 and 1782, it's in remarkable condition. It is pretty well protected from the public by the fountain itself.
Interesting more modern history. As the "mother" figure, she is the main celebration point for Real Madrid's many football championships. It's not hard to find a picture of Cibeles with a Real Madrid scarf. read more