Manhattan
I'm envisioning a Kubb set where the King is carved to look like the Empire State Building. Still square but towering up with that unique look, including the antennae tower on top (which could make it taller than regulation, but the tower could be flexible so it would be unlikely to tip the king if hit).
The Kubb's themselves would not be modified in dimensions at all, but could be woodburned to make half of them look like brownstones and the other half could look like smaller office towers (like lower Manhattan).
As a super cool add on the set could include a carved King Kong that you would place on the King just for fun, or to facilitate a William Tell variation of the game.