When talking about roman legionaries, you cant really ignore the fact theat they were great engineers, therefor, it would be cool if, when besieging a city, you would be given an option to encyrcle it, with temporary walls.
These should be made in one turn (unless the turn covers less that one week)
They should lower the number of turns untill starvation in the city
They should ofcourse be on the battle map, as they have great defensive value
There are several examples of these walls being built by the romans:
- Siege of Alesia - Caesar wanted to cut every supply line, and wanted protection against the relief armies.
- Third Servile War (spartacus) - To avoid any slaves fleeing, and to cut of their supply
- Siege of Jerusalem - Also to avoid supplies reaching the city defenders
So you can see there are examples of such walls being constructed, and those are just the ones I know about, and probably there's has been more than we know of today.