When I was last in Rome, I didn't get to see the catacombs, so this time I was determined to fit them in. These are supposed to be the biggest and best, so I booked a tour before we left. Getting there is a bit of a task, as they are quite a way out of the centre. We got the metro to the Colosseum, and caught the 118 bus from the far side. This goes down the Appian way, and will stop right outside the Catacombs.
There is a gift shop, a ticket booth, and some vending machines. You can buy tickets, but the booth shuts between 12 and 2, so make sure you get there early. The machines sell drinks and chocolates, etc, and take smaller notes, but you're better off with some loose change.
After a long wait, our large group was given a brief introduction, and then we went down. There are a lot of uneven steps, and it's a bit claustrophobic, so that's something to bear in mind. We wandered the corridors of the third level, and the guide talked us through all the points of interest. Clearly the christians had been digging away for a long time, because the area was huge, and we saw just a small part of it. We enjoyed the tour, which took about an hour, but there's little else to do once you come out. We went back to the bus stop and within minutes the 118 turned up, going back to the city. Please note - this stretch of the Appian Way is lined by high walls, and the road is very narrow. You are literally standing on the edge of a busy narrow road, so be careful. Sadly, no phots allowed.