Frías is a town located in the northern part of the province of Burgos, in Castile and León, Spain.
In 2010 it had a population of only 275 inhabitants.
Frías is a historic medieval town on a hill above the river Ebro. Now a popular tourist spot it has an impressive castle dominating the river and the twelfth-century bridge across it. It is considered to be the smallest "city" in Spain, having been given that title in 1435.
There are two convents and two churches in the town.
The gothic church of San Vitores is particularly worth visiting.
Reference: Wikipedia