Regatta draws rowers, throngs to banks of the Charles — Gallery

Some of the world's best rowers convene at boathouses in Boston and Cambridge this weekend to engage in the 51st Head of the Charles Regatta, a two-day fest of brawn, stamina and skill with oar and helm that pits 11,000 athletes against one another and the unrelenting clock.

In addition to competitors from 28 countries, the races that go on all day typically attract as many as 400,000 spectators, which can lead to clogged streets and lane closures along Soldiers Field Road/Storrow Drive in Boston; Memorial Drive in Cambridge will be closed between Western Avenue and where it begins near Mount Auburn Hospital most of the day Saturday and Sunday.

Some of the best locations to catch the races are along Memorial Drive from the starting line near Boston University's DeWolfe Boathouse, just downstream from the BU bridge across the river, to the finish line at Herter Park, just west of the Harvard University athletic fields. The three-mile course passes under seven bridges, many of which can also offer good views, where pedestrians are permitted. The first boats set off at 8 a.m. Saturday and the last race ends around 5 p.m. Sunday.

Spectators can keep an eye out for teams from their old schools while motorists trying to get somewhere in a hurry would do well to avoid the area.