Segovia
Segovia's aqueduct was built by the Romans way back in the 1st century AD. Known as Segobriga in those days, the town was an important military base.
If this castle looks familiar, it could be because it served as the model for the castle in Walt Disney's Sleeping Beauty.

It is known as the Alcázar de Segovia. Construction was begun in the 12th century, but most of the construction actually took place from 1410 until 1455. Much of it had to be rebuilt after a fire in 1862