Rome

Rome doesn't organize itself around a single old town the way a lot of European capitals do — the ancient city, the Renaissance city, and the modern city are stacked on top of each other and spill into one another block by block. You can be looking at a 2nd-century column, then order lunch at a place that's been open since the 1960s, then walk past a metro station that's still partially closed because construction crews keep hitting more ruins every time they dig.

That last part is not an exaggeration. Rome's metro has two and a half lines for a city of nearly three million people, largely because any new excavation is legally required to stop and document whatever archaeological find turns up underneath it. The practical result for visitors: buses do a lot of the heavy lifting, traffic is dense, and the historic center rewards walking over transit for anything under about 40 minutes.

Food deserves real attention here, more than in most cities where "eat well" is a throwaway line. Rome has four defining pasta dishes — cacio e pepe (cheese and pepper, deceptively simple, easy to get wrong), carbonara (egg, guanciale, pecorino, no cream despite what half the recipes outside Italy claim), amatriciana (tomato, guanciale, chili), and gricia (essentially carbonara without the egg). A restaurant that does all four well, without photos on the menu or someone outside trying to pull you in off the street, is usually a safe bet. Expect a coperto, a small per-person cover charge, on most bills — it's standard, not a scam.

The Vatican and the Colosseum are the two sites that punish poor planning the hardest. Both routinely run multi-hour queues in peak season for anyone showing up without a timed ticket, and both sell out days ahead in summer for the better entry slots. Book before you land, not after.

Trastevere, across the river from the main historic center, is where the evening pace slows down — cobblestone streets, ivy-covered buildings, and a much higher ratio of actual Romans to tourists after dark than you'll find near the Trevi Fountain, which is worth seeing once but is genuinely one of the most crowded few square meters in the city at almost any hour.