Roman city of Complutum Monument · Alcalá de Henares, Cuenca del Henares, Madrid Founded in the 1st century on the Henares plain, it preserves the layout of its forum with basilica, curia, baths and porticoes. Declared a protected archaeological zone in 1992, much of the site has been open to visitors in the open air since 2008. Photo: Raimundo Pastor (CC BY-SA 4.0) What to see and do in Alcalá de Henares