Distance from Vatican to Colossseum
 

I'm going to be in Italy in 2 weeks. We only have one full day in Rome, so need to be efficient! We have a Vatican tour booked and definitely want to see the Colosseum. How far it is from the Vatican to the Colosseum? And also to the Pantheon? Is it best to take a bus, train, taxi??

Taxi to both places. Depending upon traffic about 7-10 minutes each

you can hop on the 64 bus the (pickpocket special)it will take to both places.
For the Pantheon you get off at the largo Argentina, walk to light cross street (bookstore on other side) walk down that narrow street and you will be alongside the Pantheon walk into the square and there you are.
Return same way to bus stop Hop back on 64 get off just before Victor Emmanuel II Monument and walk in front of it and around to the via dei fori imperiali you will see the mobs as you see the coliseum on your right will be the forum on your left Trajan's Market and Column.
Or take a cab should not be more than 8-10e

thanks for the quick responses! We were thinking the bus, but with all the bad things I've read about the #64 bus, I don't know. Is it as bad as they imply?

Two points:
Yes the #64 bus is bad, but if your valuables are secure such as in a money belt you will likely be OK. We took it to no bad effect several times two years ago.
Also you will have to allow time for the lines to get in the Colosseum. Could be an hour. Your schedule is tight.

Do NOT stand in line at the Colosseum. Go to either the ticket office for the Palatine (Via di San Gregorio) or for the Roman Forum (Largo della Salara Vecchia), buy the combo Colosseum/Palatine/Roman Forum ticket (there is no single ticket for the Colosseum), and take the much, much shorter line for ticket holders.