HMS Unicorn is a super old sailing frigate that's been chillin' in Dundee, Scotland for ages. Built back in 1824, this ship never actually hit the high seas because it was used as a hulk and depot ship. It's like a time capsule from the age of sail, with its original hull still intact. Now, it's a museum ship, making it one of the oldest and most legit pieces of maritime history around. Plus, it's got a cool circular stern and a unique construction style that sets it apart from other ships of its time.