Packing for attractions

Borghese doesn't allow any bags at all - there is a free check. Coliseum doesn't permit large bags, but small backpacks or purses are ok. Pantheon does not seem to have any specific restrictions.

At both the Coliseum and the Vatican I bring a normal-to-large size purse (big enough for a DSLR camera and basic essential but not much else) and have had no trouble.

I read "packing for attraction" thinking it was a new take on the 'colour capsule' posts....haha. Now that I am over that.....
Depending when in October, it could be cool enough for a light jacket. One with pockets allows a lot to be carried on your person - at least the valuables you might be concerned about. Put a travel lock on your bag and pass it over to the storage folks. It takes me a time or two to get used to that again, but one does. Some places had separate lockers and you were given a key, but as I haven't been there for a while, I don't know what is current. At the time Borghese did that.

The only place I've ever gone that didn't allow big items and did NOT have some kind of storage facility was a private gallery in London. The Vatican Museums don't allow large backpacks. The Borghese is more liberal than they used to be. Several years ago, they pretty much required all bags to be checked, but this February, I saw lots of over-the-shoulder bags that were varied from small to large enough for a laptap.

Pro tip: if your day bag looks like a purse, they will almost never make you check it. Something sacred about a woman's handbag. If it's a backpack, off it must go--even when it's smaller than my handbag!

Way around this: choose a bag that you can carry on one shoulder, tucked under your arm, like a handbag or small tote. They're most worried about you banging your backpack into things. Men, just get a manpurse. When in Rome... literally.

If the current security situation leads to bag checks, also think about simplifying what's in the bag so the security guard can easily see down into it and you aren't disassembling the entire thing at every checkpoint. With my London purse, once I pull the DSLR camera out, it's easy for them to see I've only got pocketbook, phone and assorted pens, lip glosses, and other tiny non-weapon things rattling around in there, and I get waived through quickly.

Meanwhile, someone with a modest but full backpack is stuck at the table having to take the whole thing apart...

Thanks for that point, selkie. I will keep this in mind.

My daypack (medium/small backpack) has a carry strap, so when I approach a museum or other attractions, I just hold it by the strap. This seems to satisfy some staff, so checking it is unnecessary.