Catacombs in Rome

Pecanlady -
The various catacombs can can only be accessed with tours but you can do that when you arrive: buy a ticket at the entrances for the next guided tour in English.

Here's some info on the 3 most visited:

San Sebastiano (I've done this one):
http://www.catacombe.org/uk_index.html
Do note that if your visit is THIS Wed/Thursday, they are currently closed until after Christmas.

Catacombs of Callixtus:
https://www.catacombe.roma.it/en/index.php
This one is in the same area as S. Sebastiano and is closed on Wednesdays.

Catacombs of Priscilla:
http://www.catacombepriscilla.com/index_en.html
Closed Mondays

Editing to add: the Capuchin Crypt often comes up in catacomb discussions but as its creation was much more recent (17th century) compared to the three above, it doesn't really fall into the same category, IMHO. As well, out of respect, human remains have been removed and relocated from the publicly viewed areas of the aforementioned catacombs, and photography is not allowed.

Here's just one more for your list:

Catacomb of Domitilla:
https://www.catacombedomitilla.it/en
Closed Tuesdays

If you can busy only one Catacombes- what is the best one to see?

"Best" is a subjective term so I'd cruise some reviews and the online information of individual highlights. Obviously, S. Sebastiano is out if you are in Rome this week. I do know that Callixus/Callisto is very popular and reviews are trending a little more favorably than Domitilla but about the same as Priscilla. Depending on weather and time, Callixus would be a good choice if interested in exploring, on foot, more of the Appia Antica in that area.

I may have spoken in error: there are a few mentions of a small amount of remains visible in Domitilla but, well, that's not a reason I would choose that one.

I can recommend Walks of Italy's "Crypts, Bones & Catacombs, an Underground Tour of Rome" which includes a Capuchin Crypt visit. Sale currently on, 25% off. Excellent guide, knowledgeable and engaging. Two thumbs up, all the way. Whichever you choose, have a great time in the Eternal City.

Sounds good- where can I find this tour?

I found it - all sold out

I need Wednesday or Thursday