Castle of Alcalá la Vieja Monument · Alcalá de Henares, Cuenca del Henares, Madrid An Islamic fortress raised in the 9th century within the Middle March of al-Andalus and conquered in 1118 by the Archbishop of Toledo; what stands out today is a square outlying tower some twelve metres high. Photo: Raimundo Pastor (CC BY-SA 4.0) What to see and do in Alcalá de Henares