19. Durham: Durham Castle
Durham Castle, which was erected during the 11th century, was initially a strong-point for King Norman, and served as a way for him to display his power and prestige throughout the northern regions of the country.
The castle is now occupied by University College, Durham, but it still offers a fine example of an early bailey and motte style castle.
It is open to the general public, albeit through pre-booked guided tours. The castle sits atop a hill in the Durham Peninsula and affords beautiful views over the River Wear and across to Durham Cathedral.