Guidebooks and tourists often ignore this tiny ruin. They make a great mistake in doing so, as Soure’s castle has several unique features. First, it is on a flat plain on a riverbank in a country where castles seek out the high ground. It also has one of the earliest keeps in the country, dating from the 5th or 6th century. Finally, it has a series of rare Visigothic windows, not to mention a Roman temple. Soure had found itself in a no man’s land after the fall of the Visigothic kingdom to the Moors. The tiny castle must have seen numerous battles as Christians and Muslims fought. By the 12th century it was in Portuguese hands, but at that point the town had been abandoned. After the Moors had been expelled from Santarém in 1147, people returned to Soure. But, the castle was soon abandoned and fell into ruin. What remains is a wonderful lesson in Portuguese history, and it is more than enough to merit a visit.