Hogwarts castle tower on a wrist

Old Ivor Pryce had a stall on Saturday market, selling maps nobody wanted. Folded road maps, hill walks, the odd engraving of a valley that had been drowned for a reservoir. One wet morning in March a boy came up from the station with a sheet of brown paper under his arm, and he would not sell it. He wanted it framed. Ivor unrolled it on the trestle and there was a castle drawn on the hill above the town, seven towers, a flag on the tallest one, and a word along the flag's edge in letters so small you needed a lens. The boy said his mother had drawn it in the blackout, from memory, and she had never once set foot on that hill.

Ivor said there was no such hill. The boy said there was, behind the chapel, if you knew which gap in the hedge to take. Nobody in the Crown believed him. Then the Tuesday after, the gap was open, and a tower no higher than a man stood among the nettles with its pennant curling in a wind that wasn't blowing.

Ivor went up with his magnifier and read the word on the flag. Then he went home, took out his pen, and inked the same pennant on the inside of his own cuff, small and neat, the way you'd sign for a parcel. He never said why. The boy was never seen again, but the tower is still up there, and if you go looking you'll find it. It only opens for people who already have a map to lose.