Related Clues:
- Backdrops in 'Teenage Mutant Ninja Turtles' films
- Large water pipes
- Underground maze
- City system
- Major water carriers
- Underground channels
- Prodigious pipes
- Drain pipes
- Water or gas pipes
- Big conduits
- They may be accessed via manholes
- Pennywise's place, in 'It'
- Small vessels, those carrying waste
- Some waste conduits
- Waste channels