 During the Muslim period an "Alcázar" (fortress) was built by the mid-9th century, as well as the Bridge over the Henares (its construction has been tentatively dated by the late 10th century or early 11th century).City walls protecting the city were also built then.Guadalajara was part of the territory annexed by Alfonso VI of León-Castile in the 1085 conquest of the Taifa of Toledo, with the city of Guadalajara surrendering and offering no resistance.