Related Clues:
- Obstacles designed to prevent advance or progress
- Objects erected to control progress or access as by crowds
- Erections to control or impede advances
- Onslaughts
- Long attacks
- Drawn-out war campaigns
- Military blockades
- Protracted battles
- Extended attacks
- They're put up to block or protect
- Obstacles to movement
- Obstructions are mostly clogging pipes
- Advocates avoiding street obstacles
- Military actions of isolation and attack
- City investments?