ROMA now has chariots that will ferry you around ROMA's three sims.
Outside the Pompeii Tavern in ROMA you can catch either the 'Subura Loop' chariot that will take you around the outer ring road of the Subura, or the 'Ostia Express' that will take you directly to the Ostia settlement in the northeastern corner of the Transtiberim sim.
Beside the main gate of Ostia, you can catch a chariot that will bring you right back to the plaza before the Pompeii Tavern.
It is possible, once you learn the routes, to hop on a chariot and hop off when you reach the area of ROMA you wish to visit.
It is a new, fun way to move around ROMA. Hope you enjoy it!