That is impossible for now, there is a road that leads from the main entrance to a parking area near Mystery Castle and River Quest entrance, it was taking stairs up or stairs down into a tunnel.I kinda wish they just built a tunnel to the plaza before Chiapas’s entrance, tbh. It’s awkward having to go up a flight of stairs in Berlin only to then have to descend another flight of stairs in Mexico just to get to it. They tore out a section of the Berlin street to make the Rookburgh tunnel, so this shouldn’t be unfeasible.