Related Clues:
- Son unwell -- one lies horizontally
- Place for potted plants
- Pie perch, perhaps
- Submerged underwater shelf
- Piece under a door
- Part of a tall building
- Shelf where there's incomplete book of accounts
- Window box support
- Base of a window
- It's under the window
- Horizontal intrusion of igneous rock between sedimentaries, as in much of Hadrian's Wall
- Place for potted herbs
- Sun tea brewing spot
- Natural projection
- Place to set a candle, maybe