Guadalajara's old town is compact and walkable, and the main monuments cluster within a few hundred metres of each other. The Palacio del Infantado is the centrepiece — one of the great examples of Spanish late Gothic architecture, with a facade covered in diamond-point stone bosses and an interior courtyard that still stops people in their tracks. Around it, a handful of churches and palaces from the same Mendoza family building campaign of the 15th and 16th centuries survive in reasonable condition.
The Torre de Álvar Fáñez provides a visual anchor for the old town from below. The cathedral — technically a co-cathedral — lacks the grandeur of the palace but is historically significant. The church of Santiago el Mayor, with its distinctive tower, is worth a stop, as is San Ginés. The Thursday market brings the town to life around the Plaza Mayor.
For those interested in modern history, the Battle of Guadalajara in 1937 — where Italian fascist forces were defeated by Republican troops — was one of the more significant engagements of the Spanish Civil War and is documented in the Provincial Museum.