Walking the streets of Rome with a double stroller....

Is this a double wide stroller or one that has the seats behind each other? What about Baby Bjorns? What do you plan on doing with the kids once you park the stroller?

https://www.google.com/maps/place/Tiffany+%26+Co./@41.9057282,12.4837207,3a,75y,130.8h,72.49t/data=!3m6!1e1!3m4!1sN6qPKFln8JIb44wreS4zow!2e0!7i16384!8i8192!4m14!1m7!3m6!1s0x132f60541678ae75:0x7fc0d4978aae690f!2sSpanish+Steps!8m2!3d41.90599!4d12.482775!16zL20vMDFfamxz!3m5!1s0x132f6055a0e245c7:0x306d551d80a6ced1!8m2!3d41.9067101!4d12.4808237!16s%2Fg%2F1tgyn1xq?coh=205409&entry=ttu

Random sample of streets, note cobble stone, and width of sidewalks. This near the Spanish Steps. I will let you decide how difficult it is.

If you use a single stroller, a tandem style seems the better choice.

On YouTube you can find videos which document current walks through various parts of the city - that would give you an idea of what you may encounter..

We encountered narrow streets leading to and from the Pantheon which were so crowded as to be almost impassible. So I would hope the the stroller is double front to back, and not side by side.

Tandem style pushchairs are not easy to manoeuvre. I wouldn’t recommend them. The best double pushchair I’ve ever used is the Out and About Nipper 360, a 3 wheel off road style. I have no idea if this is available in other countries but it would be ideal for the uneven surfaces of Rome. It doesn’t fold up small but I think ease of use in the destination would be more important to me with such small kids.

I wouldn't try it with either a side-by-side or a tandem stroller. Many of the streets just aren't designed for taking up that sort of space, and you're going to be faced with stairs here and there. Your best bet for sightseeing in certain areas are putting them in back carriers to be able move around more nimbly and to get the kids UP and away from the nether regions of heavy crowds. If they're just too heavy to carry for long periods of time and/or it's too hot, then bring easily foldable strollers, one for each of them.

We do plan on visiting the main stops.

You haven't said when you'll be traveling but you are aware than the main attractions aren't exactly stop-bys, right? You're going to need to have advance, timed-entry tickets for the biggies (Colosseum + Vatican Museums + Galleria Borghese).

Strollers are allowed in the Vatican Museums but I don't advise trying to do that one with two toddlers. The crowds are dense, it can be hot, noisy and uncomfortable, you'd have steps to deal with, and it wouldn't be pleasant for them (or you) at all. If it's a must for you, opt for back barriers or individual strollers. St. Peter's doesn't allow strollers but they do have a cloakroom for checking them.
https://www.basilicasanpietro.va/en/experience-the-basilica/visits.html

Galleria Borghese: Strollers for ages under 2 are allowed but very likely not larger than single-child models so you'd need two. The "Mama Loves Rome" site advises soft structured carriers for this one instead of strollers but go with wheels if carriers don't work for you. I don't believe you'd be allowed to bring diaper bags or food inside the galleries.
https://galleriaborghese.beniculturali.it/en/info/servizi/
https://mamalovesrome.com/borghese-gallery-with-kids-best-things-to-see/

Colosseum: strollers are OK (no place to check them) but it'll be crowded and I wouldn't do it with a tandem or double.

Pantheon: no issues with strollers here; it's all flat.

Some other info from "Mama Loves Rome" you might find useful, especially attractions she recommends using carriers versus strollers for. She also has a few recommendations for stroller and carrier models :O)
https://mamalovesrome.com/visiting-rome-with-toddlers/

I carried my son in. a back pack carrier until he was 2 -- any change either of your babies could be carried this way. A single stroller paired with a backpack would be easier. Or two strollers.

I can recommend ‘Four Seasons in Rome’ by Anthony Doerr. It’s about spending a year in Rome on a grant from the National Endowment of the Arts right after his twins were born. It’s not a long book and it’s a wonderful look at Italian life and he does talk a lot about maneuvering around Rome with 2 little ones.

All of this information is great! Thank you everyone!! More info the better to help us make this choice.