Blackness Castle in Falkirk

You're standing at Blackness Castle, on the south shore of the Firth of Forth. Take a good look at its shape. The castle juts out into the water, long and narrow. That's why people call it the ship that never sailed. The north tower, the tip pointing out to sea, is known as the stem. The south tower is the stern. And that separate tower in the middle? That's the main mast.