a group of movable bridges.
Put the bridges across minor rivers or streams.
(The bridges are not appropriate to the terrain.)
Bridge 1 Cost: $5,000
Maintenance fee per day: $5 per day; Category: Deco -> Other Bridge 2 Cost: $10,000
Maintenance cost: $10 per day; category: Deco -> Other Bridge 3; cost: $25,000.
Maintenance cost per day: $15
Price: $15,000; Category: Deco -> Other Bridge 4.
Upkeep: $15 per day; Category: Deco -> Other

Thanks to Razak