Plaza San Martín, in the ancient city of Segovia, goes by another name: Plaza de las Sirenas, or the Square of the Mermaids. While the origins of its nickname remain unknown, part of the story can be explained by the mythological, sphinx-like sculptures that surround the plaza. These sculptures, known as sirenas, don’t really resemble mermaids at all. Bearing the heads of women and the bodies of lions, they appear to be mystical yet landlubbing sphinxes. In 1850, the city council commissioned sculptor Francisco Bellver y Collazos to create sculptures…