Over the past couple of years, the Celio -- the area of the Celian Hill -- has experienced a resurgence, with the opening of a few upper-level hotels and a handful of better restaurants. Rising housing costs in other centro storico (historic center) zones have provided a miniboom in apartment rentals in the area, too, and these new residents need places to eat, drink, and be merry. One of these high-quality restaurants, near the Colosseum, is Ai Tre Scalini, and a welcome surprise it is. Sit outside in warm weather, but if it gets too hot, the naturally cool rooms on the lower level are fantastically refreshing. Sample chef Angelo Annarumi's playful salmon roulades with ricotta cheese and pink grapefruit, or the unusual radicchio and cheese-stuffed zagnolotti (small ravioli) in a delicious lobster sauce. A wide variety of second courses, from orata in crosta di patate con vongole (gilthead bream topped with crunchy potatoes and sprinkled with tasty baby clams) to simple beef with rosemary, are all served with flair.