Sandcastle

From PatchworkWiki

The sandcastle is visible from some distance away. It is a squarish castle, with towers, battlements, arrow-slit windows, a portcullis and a moat. Surrounding it are sandbars, across which water laps, rising at night up the castle walls.

Peculiarly, this castle does indeed seem to be made of sand, but sand that has vitrified enough to be used as an apparently indestructable building material.

Although anyone may enter the sandcastle and indeed build 'normal' sandcastles from the sand around, only children (or rather those under the age of 18) are capable of making changes to the castle itself.