This Portugal map has been primarily designed for 3 players (though also playable with 2 or even 4, though super tight) and features Portugal during the height of its industrial development (1855-65). This map adds quite a few nuances to the base game such as:
a.) Banks were hesitant to invest in the industrial sector so loans return $1 less for each additional loan after the first.
b.) Railway expansion was highly encouraged - certain rails are worth $4 at the end of the game instead of $2 and there are bonus VP for the player who finishes with the most VP.
c.) Government debt was mounting rapidly due to poor management so to simulate this waste, corruption, and poor economy, there is always a region or industry where you CANNOT build.
...and many more!
Players must navigate the map's tightness - don't forget the option to combine both actions to build anywhere! - and suffocating economy to try and build a prosperous network.