tell by the faces of the people how great a time they were having."

Rome

It's a spring race with generally mild temperatures through one of the world's great cities. Although Rome is known for its hills, the marathon course is generally flat. One challenge can be some narrow, cobblestone streets. The race starts and ends near the ancient Colosseum. More than 13,300 runners from across the globe finished this year's race.

History: The race, which began in 1982, has been dominated in recent years by African men (12 straight wins) and women (nine straight).

Key feature: Costumed Roman Legionaries salute runners at the finish and clang their shields with their spears or swords for encouragement.

Scenic highlight: The route passes landmarks such as the Trevi Fountain, Saint Peter's Basilica, the Vatican, theSpanish steps and the Piazza Venezia. Live music is played at several points along the route.

Quotable: "Enthusiastic Italians continually shout 'Bravo!' to lift your tiring spirit" along the route, Lopez said.

Tokyo

It's a relatively new race, begun in 2007, and one that's flat (just 129 feet of elevation change between the lowest and highest points) and attractive to elite runners. It's also popular. About 300,000 applications were received for this year's race, which was limited to 36,000 (with most chosen by lottery). More than 1.5 million spectators turn out each year. The course will be part of the Olympics in 2020.

History: Since its start, the race has produced fast times. Kipsang (2:03:58) and fellow Kenyan Sarah Chepchirchir (2:19:47) set course records this year.

Key feature: The route has recently been