A line of red paint or red brick on the sidewalk, the 3-mile Freedom Trail links 16 historic sights, many of them associated with the Revolution and the early days of the United States. The route cuts across downtown, passing through the busy shopping area around Downtown Crossing, the Financial District, and the North End on the way to Charlestown. Markers identify the stops, and plaques point the way from one to the next.

The nonprofit Freedom Trail Foundation (tel. 617/227-8800; www.thefreedomtrail.org) is an excellent resource as you plan your visit. Call for a guide or, even better, check out the interactive website. If you're interested, it's the only way to rub gravestones legally.

This section lists the stops on the trail in order, from Boston Common to the Bunker Hill Monument. Note that this is the suggested route, and nobody's checking up on you. You don't have to visit every stop or even go in order -- you can skip around, start in Charlestown and work backward, visit different sights on different days, or even (horrors!) omit some sights. Here's a suggestion: If you find yourself sighing and saying "should" a lot, take a break.

A hard-core history fiend who peers at every artifact and reads every plaque can easily spend 4 hours along the trail. A family with restless children will probably appreciate the enforced efficiency of a free 90-minute ranger-led tour. The excursions, from the Boston National Historic Park Visitor Center, 15 State St. (tel. 617/242-5642; www.nps.gov/bost), cover the "heart" of the trail, from the Old South Meeting House to the Old North Church. At press time, tours were offered daily from mid-April to November. You don't need a reservation, but call for schedules and to check whether off-season tours are available.

The best time to start on the trail is in the morning. During the summer and fall, aim for a weekday if possible. Try not to set out later than midafternoon, because attractions will be closing and you'll run into the evening rush hour.