Land, drop your bag, and walk straight into the waterfront. Begin at the Rose Kennedy Greenway, the ribbon of parkland threading the North End to the harbor. Overcast and 57°F today, so layer a sweater under a light rain shell and comfortable walking shoes. The Greenway's fountains, mosaics, and the turning October foliage make for a slow, free introduction to the city on foot. Rainy day alternative: duck into the nearby Boston Public Market to stay dry while still soaking up the local scene.

Cut over to Boston Public Market, an indoor, year-round hall of New England makers (100 Hanover St). This is your foodie landing pad: grab a lobster roll, a cup of clam chowder, or a cider doughnut, all under $15, and eat at the communal counters where solo dining feels completely natural. Open daily, but confirm hours before visiting.

Wander five minutes to Haymarket, the centuries-old open-air produce and fish market operating Fridays and Saturdays (lighter on Thursdays, but the surrounding stalls and alleys are atmospheric any day). Thread into the North End's narrow lanes afterward for golden-hour window-light on brick.

Dinner at La Famiglia Giorgio's Restaurant (112 Salem St), a boisterous, old-school North End Italian institution with huge portions and a warm counter-friendly vibe. Order a plate you can't finish and carry the rest back. If La Famiglia Giorgio's is fully booked or closed, try another North End trattoria along Salem or Hanover Street nearby. Nightcap option: the live-music Beehive Restaurant over in the South End if you want a late jazz set in a candlelit room.

Clear skies and 55°F, the perfect crisp day for water and nature. Head to the ferry departure point near Long Wharf for the Boston Harbor Islands National & State Park. Check the fall ferry schedule in advance, as October runs reduced service; a round-trip to Georges Island lets you roam Civil War fort ruins and open shoreline with sweeping skyline views. Pack a windbreaker, it's cooler on the water. Rainy day alternative: if weather or ferry schedules scrap the trip, spend the morning indoors at the Boston Public Market grazing and warming up before your afternoon museum.

Back on land, make your way to the Isabella Stewart Gardner Museum (25 Evans Way), a Venetian-style palazzo built around a glass-roofed courtyard garden. Admission runs around $20; it's deeply atmospheric, intimate, and ideal for a solo wander. (Fun fact worth knowing: anyone named Isabella gets in free.) Hours vary, so confirm before visiting.

Stroll the nearby stretch and cut toward MassArt Art Museum (621 Huntington Ave), a free contemporary art space that's a good low-key culture hit before dinner, no ticket required. Hours vary, so confirm before visiting.

Dinner at The Salty Pig (130 Dartmouth St) in Back Bay, a cozy spot famous for charcuterie boards and pizzas, with counter seating that suits a solo traveler. Keep it to a shared board and a glass and you'll stay near budget. If The Salty Pig is fully booked or closed, try a nearby Back Bay spot along Dartmouth or Boylston Street. After, walk Newbury Street's boutique-lined blocks as the lamps come on.

Slow start, then brunch at Buttermilk & Bourbon - Back Bay (160 Commonwealth Ave), a New Orleans-leaning spot with excellent biscuits and a lively counter. Arrive early to beat the weekend wait. If Buttermilk & Bourbon is fully booked or closed, try another Back Bay brunch spot nearby. Afterward, drift down tree-lined Commonwealth Avenue Mall, one of the city's prettiest walking corridors in peak fall color.

Catch the weekend-only SoWa Open Market (500 Harrison Ave), a sprawling South End gathering of local makers, vintage sellers, and food trucks. It's a lively street-level foodie-and-crafts scene, perfect for a last unhurried graze and a recipe-worthy bite to carry home. Running Saturdays through the fall season; hours vary, so confirm before visiting. Rainy day alternative: if the market is washed out, browse the indoor galleries of the SoWa Art + Design District nearby.

Leave the South End by early-to-mid afternoon to allow buffer time. Take the Silver Line Way bus (the SL1), which runs directly from South Station to Logan International Airport and is free in the outbound-to-airport direction, no transfers, fully walkable from the Seaport side. Allow at least three hours before your long international flight back to Iran.