“The Horse Castle” is one of two “tuff rings” situated in the northeastern part of the country. This one is about 10.000 years old and the other, Hverfjall, on lake Myvatn is 2500 years old. The farmers on lake Myvatn used to graze their horses in this area and used the crater as a pen when they were rounding them up in autumn before driving them back home. There is a track all the way into the concave of the crater, where it looks almost like an amphitheatre. The road to Askja is just east of the tuff ring and the crossing on road #1 is very close.