Building fortifications during siege

[Lt Gisgo]

I read that you can improve a pop centers defensive values using order 600 during a siege but can you build fortifications using 609 during a siege?

[uncledarkside2]

Yes you can build them to break the seat siege

[Eregnon]

Unfortunately, building a castle no longer automatically breaks a siege, since they don't stop sieges anymore.

[Lt Gisgo]

Thanks. My intent was just to try to increase my defense value beyond his attack value.