Quote Originally Posted by Mount Suribachi
Yes, but the chain of castles took years, decades even to build. IIRC it was good ole Edward Longshanks who started it
A decade = 5 turns

Quote Originally Posted by the_mango55
1. watchtower - 200
2. fort - 500
3. keep - 1500 - 2 turns
4. large keep - 5000 - 5 turns