What's a good 3-day itinerary for Reykjavik?

Reykjavik's walkable core fits inside a single postcode, 101. Start Day 1 at Hallgrímskirkja, the concrete church that took 41 years to complete before its 1986 consecration. The tower elevator costs 1,200 ISK (about $10) and gives a 360-degree view of corrugated-iron rooftops painted in reds, greens, and blues. Walk south down Skólavörðustígur, the sloping street lined with wool shops and ceramic studios, to Laugavegur. Grab a pylsur at Bæjarins Beztu near Tryggvagata, the hot dog stand open since 1937. One with everything costs around 600 ISK. Continue to Harpa, the concert hall on the waterfront whose glass panels shift color with the cloud cover. The Old Harbor sits 400 meters south. Sægreifinn on Geirsgata sells lobster soup for about 2,800 ISK, served in a styrofoam cup at communal tables. Wind off the North Atlantic tends to cut through layers here, so a wind-resistant shell beats a heavy coat. Dinner at Messinn on Lækjargata 6b, where the signature fish pan runs 3,900 to 5,200 ISK.

Day 2 moves east. The National Museum of Iceland on Suðurgata, founded in 1863, covers over 1,100 years of settlement history across two floors. Allow 90 minutes. The permanent collection starts with a Viking-era longboat nail and ends at a 1950s fishing-village kitchen that still carries a faint cod-oil smell. Walk 15 minutes east to Hlemmur Mathöll, the food hall at the old bus terminal on Laugavegur 107. Skál offers lamb burgers for 2,700 ISK. After lunch, bus route 18 runs south to Perlan in about 12 minutes. The museum inside Perlan, built in 1991 atop six hot-water storage tanks, includes a fabricated ice cave held at -10°C. You feel the cold on exposed skin within seconds. The observation deck reaches toward Esja across the bay and, on clear days, the Snæfellsjökull glacier 120 km to the northwest. Close Day 2 at Laugardalslaug thermal pool, where the 40°C hot pot costs 1,150 ISK. Dinner afterward at Matur og Drykkur on Grandagarður 2 in Grandi, where mains run about 5,500 ISK.

Day 3 covers the harbor edge and Viðey Island. Start at Höfði on Borgartún, the 1909 house where Reagan and Gorbachev held their October 1986 summit. The interior is closed, but the shoreline path takes 20 minutes. Bus route 16 reaches Skarfabakki pier in about 10 minutes, where the Viðey ferry departs hourly from mid-May through September for 1,800 ISK round trip. The island covers 1.7 square kilometers of grass, basalt, and wind. Yoko Ono's Imagine Peace Tower, a light column dedicated to John Lennon in 2007, stands on the south shore. It lights only between October 9 and December 8, so in September you see the stone base without the beam. Worth noting, Viðey has no cars and no shops. The only sounds are gravel under your shoes and the occasional Arctic tern screaming overhead. Return by 3 PM, then bus west to Grótta lighthouse on the Seltjarnarnes peninsula for the afternoon. Dinner at Café Loki near Hallgrímskirkja, where fermented shark (hákarl) runs 1,600 ISK and the rye bread ice cream is better than it sounds.

September in Reykjavik currently sits around 10°C but feels closer to 7°C with the wind chill. Overcast is the default here, not the exception. Layers beat bulk. The city scores 9.3 out of 10 for solo-traveler safety (see the TTDI Solo-Safety Index), and the compact layout keeps you within a 15-minute walk of your hotel most of the time. Budget 8,000 to 12,000 ISK ($66 to $99) per day for meals at the places named above, more with wine at dinner. A glass of house red starts around 2,000 ISK at most restaurants. Total walking across the three days comes to about 18 km, none of it steep. Strætó bus fare runs 550 ISK per ride through the app. Tap water comes from glacial runoff and tastes clean with a faint mineral note. The sulfur smell from hot-water taps is harmless and fades within a day. Beer and wine are sold only at Vínbúðin state shops, with the central 101 location closing at 18:00 on weekdays.