You can walk by the Coliseum...
You can walk by the Coliseum at any time. You can get there virtually through any transportation (bus, train, motorcycle, walking, you name it).
Just know that during the summertime, tourists like you and me swarm in and it gets a bit crowded. Try to go on the off season if you can.


Temple of Antoninus and Faustina
me and She Wolf
Detail on the arch
The whole basilica.