Red Castle

The ruins of Red Castle sit on a rocky promontory just outside Arbroath, a proper dramatic spot where the North Sea does its best to batter the place into oblivion. What you're looking at is a 13th-century fortress that's seen better days - the stone is genuinely red in certain light, which is where it gets its name. You can walk right up to the ruins and poke around the remains, though there's not much standing tall enough to go inside these days. The views across the Angus coastline are excellent, especially if the weather's being cooperative.

Historically minded visitors will find this worthwhile - it was a significant medieval stronghold, and there's proper atmosphere to the place, particularly on grey afternoons when the wind picks up off the water. Families with energetic kids might get an hour out of it before everyone gets cold. The walk from the car park is straightforward enough, though the path can be muddy in wet weather.

If you're staying at The Grange Glamping just down the road, this makes an easy afternoon excursion. There's no charge to visit, and no formal opening hours - you just turn up. Allow an hour to properly explore and take in the setting. Go when the tide's out if you can; the beach access makes the whole experience less claustrophobic. Best visited in decent visibility so you can actually see where you are.