Roman emperors like Hadrian and Diocletian covered their lavish villas in marble and built vast bathhouses that were essentially the world’s first spas, so it should come as no surprise that many of the Eternal City’s most luxurious hotels pay homage to them in one way or another. After all, the city has been drawing travelers since the days of the Roman Empire. During the Grand Tour era in the 18th century, poets, painters, and aristocrats flocked here to admire the city’s ancient ruins and baroque art and architecture—still valid reasons to visit now, though today’s travelers will find plenty of modern pleasures as well. Over the past few years, the city’s hotel scene has exploded. International hotel groups like Anantara and Six Senses have set up their first hotels in the city, Italian brands including Bulgari and ROMEO have expanded their footprint with openings, and historic stalwarts such as..