Boston is one of America's oldest cities, a place where the Revolutionary War story, Harvard and MIT, Irish and Italian neighborhoods, and a thriving tech and medical economy sit side by side. It's compact and easy to explore on foot, with brick sidewalks, harbor views, great seafood and passionate sports fans (Red Sox, Celtics, Bruins, Patriots).

Come for the history, the food and the neighborhoods, and walk as much as you can. Hotels are expensive, but many attractions are free.

Spring (April to May) is cool and changeable. The Boston Marathon on Patriots' Day in April draws big crowds, and late May brings college graduations.

Summer (June to August) is warm and humid, with harbor cruises, outdoor dining and baseball. Best for atmosphere, and prices peak.

Fall (September to October) has crisp days, fall color and student arrivals. Best overall, though hotels fill quickly.

Winter (December to March) is cold and snowy, with nor'easters. Holiday lights and quieter museums offer good value.

Check the events calendar. Graduations, the marathon, major concerts, Red Sox homestands and conventions raise prices sharply.

2 days covers the Freedom Trail, the North End and a museum.

3 days (recommended) adds Cambridge, the Back Bay and a proper evening.

4 to 5 days adds Salem, Concord and Lexington, Plymouth or Cape Cod.

Day 1, the Freedom Trail: follow the red line through Boston Common, the Massachusetts State House, the Granary Burying Ground, the Old State House and Faneuil Hall. Lunch at Quincy Market or the North End. Afternoon at Paul Revere's house, the Old North Church and the USS Constitution in Charlestown. Evening dinner in the North End (try pasta and a cannoli).

Day 2, Back Bay and culture: morning in the Public Garden (swan boats in season) and a walk along Newbury Street. Afternoon at the Museum of Fine Arts or the Isabella Stewart Gardner Museum. Evening at Fenway Park for a game, or a show in the Theater District.

Day 3, choose your own: cross to Cambridge for Harvard Yard, MIT and Harvard Square, or take a harbor cruise or ferry. Or go farther: Salem for witch history (by ferry or Commuter Rail), or Concord and Lexington for Revolutionary War sites.

Downtown, Faneuil Hall and the Waterfront suit first-timers: close to the Freedom Trail, busy and touristy.

The North End suits restaurants and a historic feel: charming, small and often costly.

Back Bay suits shopping, Newbury Street and a polished feel: central and elegant.

Beacon Hill suits postcard streets and quiet evenings: pretty, with limited hotels.

Seaport and Cambridge suit modern hotels, restaurants and universities: easy transit and a different vibe.

Boston is very walkable, and many sights are within a short stroll. The MBTA ("the T") runs subway lines (Red, Orange, Blue and Green), the Silver Line buses and Commuter Rail. Use a CharlieCard, CharlieTicket or contactless payment, and check current fares and service alerts. Service typically ends in the early hours of the morning, so plan your late-night ride.

From Logan Airport, the free Silver Line (SL1) goes to South Station, and a free shuttle connects to the Blue Line. Rideshare and taxis are widely available.

Don't rent a car in the city: traffic is heavy, parking is scarce and expensive, and streets are confusing. If you want day trips, take Commuter Rail or rent only for those days. Bluebikes and scooters are available.

Freedom Trail: the 2.5-mile red-brick line links 16 historic sites, many of them free. Guided tours and audio guides are available.

USS Constitution: a free tour requires photo ID and security screening.

Food: clam chowder, lobster rolls, Italian cannoli and pastries in the North End, Boston cream pie and baked beans. Seafood is excellent but pricey.

Walking surfaces: brick, cobblestones and hills can be slippery, especially in winter or rain.

Last call is 2 a.m., and public transit closes earlier. Tipping 18 to 20% is standard.

Boston is one of the safer major US cities, and most visitors have no trouble. Use normal precautions: keep valuables secure in crowds and on the T, and be aware late at night. Some neighborhoods away from the tourist core are less comfortable after dark; use rideshare if unsure.

In winter, ice and snow cause falls and delays; dress warmly and wear boots with traction. In summer, watch for heat and humidity.

Emergencies: dial 911. Boston has world-renowned hospitals and many urgent-care clinics and pharmacies. If you take prescription medications, bring a buffer supply.

Comfortable walking shoes with good grip, layers, a compact umbrella or rain jacket, a warm coat, hat and gloves in winter, sunscreen and a water bottle in summer, and a small bag for crowded transit.