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Fellini’s ROMA or SATYRICON are good condiments before or after your visit.
If you only have 36 hours, buy tickets to the Forum, Colosseum, Vatican, ahead of time (you should do that anyway to avoid missing out). Walk to those places and other landmarks, get a little lost, eat what looks good. This really isn’t a guide lol.
Rome is a walking city and the very best way to see it is to walk until you are starving and find just the right little trattoria for lunch, then walk off all the incredible food you stuffed yourself with, stop for a gelato or cappuccino and then find a great little place for dinner.
Walking in Julius Caesar’s footsteps is mind blowing.
Stop in churches, big and small; take a tour of St. Peter’s for an amazing experience no matter your religion, definitely walk through the ruins of the Forum (il Foro). My wife’s favorite was the Palatine Hill next to the Forum.
When visitors ask me for travel tips to the city I adore, they includes churches where Caravaggios are in small side chapels, the Scavi tour beneath St. Peter’s Basilica (becoming ever more difficult to visit as people learn about it),
The NYRB’s Secrets of Rome (there’s a series of these guides) is the absolute best, with suggestions by classicists, writers, musicians etc. It’s also a great read
In 2007, I traveled to Rome for 12 days to attend a consistory for new Cardinals, at St. Peters. Each morning I would get up at 5:00 AM and run a different 7 mile loop through the deserted streets. I did repeats at Circus Maximus, a run on the Appian Way, a dawn run by the Coliseum and so much more. It is one of the most exhilarating experiences I have had in my 75 years. Yes, Rome is truly the “Eternal City”
I’m glad this article suggested visiting Palazzo Colonna. It’s spectacular. Just remember, it’s only open on Saturdays.

Also, the Galleria Borghese is an amazing place. You must make reservations and you can only visit for 2 hours. Skip private guides and just use the audio guide.
Begin and never end with visiting the museums and ruined cultural icons of the Roman Empire fka Republic. .

Must see is the Roman Forum and environs. And the hill that overlooks the Circus Maximus.

Must see is the Colloseum and St. Peter’s.

Along with the Vatican Museum.

See where Julius Caesar was funeralized. And where he was assassinated.
The Vatican Museum was the only small disappointment. You had to sit down, keep quiet, could not take pictures and it was freezing in the place(Sistine Chapel), unlike other places that were open, friendly and camera friendly. Similar with Raphael’s Masterpiece School of Athens, not user friendly in the Vatican Museum.
I am happy that this writer focused on the sites, foods and sounds the younger hip crowd might be interested in. This means a few less visitors to the Forum, my favorite art galleries, churches filled Caravaggios, and favorite shopping/food streets around Via dei Coronari.
Before you go, learn a few words in Italian starting with greetings and thanks, asking basic questions, and words/metric measures needed for directions and orientation (if you are told “Go three hundred metres and then turn left for another hundred metres”, will you be able to gauge that?).

Numbers, left/right, and days/months are always helpful.

And learn, as best as you can, how to say “Good day! Excuse me: I don’t speak Italian. Do you speak English”?

Actually, these suggestions apply to any place you visit where you don’t speak the language. I am lucky to have mastered the basics for all of our neighbours, except no matter how hard I try I find Hungarian undecipherable. But I can at least say “Elnézést: nem beszélek magyarul” and – the most important word – “Köszönöm”.

The slightest indication that you are willing to try will get you a long way.
I would encourage folks to take a trip to the Testaccio Market in the neighborhood of the same name. It’s a low-key market in a charming working-class (though gentrifying) neighborhood, and the market happens to sell the best sandwiches in the city – specifically at Mordi e Vai, an old-school Roman sandwich shop. If it’s not one of the best sandwiches you’ve ever had, you can come back and yell at me in the comments.
It doesn’t mention basics (spectacular ones!) like the Roman Forum (though the article includes a photograph of it), the Villa Borghese, the Roman Baths, the Vatican, St. Peter’s, the Spanish Steps, the Trevi fountain, or the Pantheon. This is simply perverse.
the unbelievable church art, available: For example: 6 Caravaggio’s, dozens of examples of Raphael’s and Bernini’s work that can be admired and enjoyed – free of charge.
The palazzo colonna gallery mentioned in the article, that’s the location of the, i guess “magnificent” is the word i have to use to describe it, art filled chamber that is the scene of the movie’s last few minutes. You’ll have to imagine the color as the movie’s in b&w. I didn’t notice this mentioned, the tie o roman holiday, in the few comments i scrolled so i figured i’d mention it before i went on to another article. I’ve been to rome a couple of times myself, never did get to the palazzo. The sistine chapel was wonder enough for me.
Map out a walking tour to visit all of the Bernini sculptures scattered throughout the city – in piazzas, carved into corners, in churches!
the small, but famously beautiful Hotel Raphaël (where all of Craxi socialist colleagues used to hang out–political intrigue! fun!). I love the Navona area and recommend dinner at L’eau Vive (Italian/French, yes!) where you can eat next to Vatican cardinals and the occasional movie star, while listening to the Ave Maria at 10 pm and enjoying the kind and attentive waitress nuns: wonderful food in an ambiance très bizzare!