Oakham Castle certainly doesn’t look like your typical castle. Nonetheless, the squat stone building, which was originally the Great Hall to a larger complex, still holds intriguing treasures within its 12th-century walls.

More than 230 ornate, oversized horseshoes adorn the castle’s interior. They’re the result of a unique custom associated with the castle that still exists today. According to the tradition, when a peer of the realm visits the town of Oakham, he or she must give a horseshoe to the Lord of the Manor.

It’s unclear why or when the tradition began. It’s believed to be connected with Walchelin de Ferriers, for whom the castle was built. The Ferrers came from a part of Normandy known for its ironwork, and the family name derives from the French word for “farrier.” The family’s symbol is even a horseshoe.

Early on, the horseshoes were nailed to the castle gate and door, rendering many corroded and difficult to read. The oldest surviving horseshoe on display was presented by Edward IV in 1470 after his victory at the nearby Battle of Losecoat Field. Over time, the horseshoes became more ornate, with their tops adorned with a coronet denoting the rank of their donor. The tradition continues to this day, with the most recent being presented by the Duchess of Cornwall in 2014.