A main attraction of Santiago do Cacem is the castle on top of the hill with its 5 towers, overlooking the close coastline of the atlantic ocean, the soft hills of the alentejo landscape and the narrow alleys of the old town.
Is is supposedly of arab origin and dates back to the 8th century, and later passed definitely into Portuguese possession under King D.Afonso 2nd in the 12th century and was given to the Knights of the order of St. Jacob. Is is classified as a national momnument.
In the southeast of the castle walls the impressive church of Matiz was build, probably in the 13th century and a national monument as well.
There is a history old city behind the castle and a newer city center arounf the market hall.