Overlooking Snowdonia’s Llanberis Pass and the waters of Llyn Padarn, is the ruin of Dolbadarn Castle.
This castle has been estimated as having been built between the 12th and 13th century, and the tower's design is said to have been inspired by similar fortresses built by Llywelyn the Great's rivals.
This site is completely free to see, but it's a bit of a trek to reach - so be sure to wear appropriate shoes. When you reach the castle, you can walk to the top to see an epic view!
Concessions: Free entry