Guide de ville
Colombo CMB: What to Do on a Layover
Pettah market in 3 hours: fabric stalls, kottu roti, Dutch colonial lanes.
Getting from the airport
CMB to city center: 40 minutes by bus (Airport Express Bus). Trains run every 30 minutes. Service runs 06:00 to 22:00. Skip the taxi unless your connection is under 5 hours.
What to do in Colombo
The stops worth making: Colombo Fort & Pettah, Gangarama Temple, Galle Face Green, Keells Supermarket spices. Rated above 4.4: Colombo Lotus Tower (4.5), Gangaramaya Temple (4.6), Viharamahadevi Park (4.4), Independence Square (4.6), St. Anthony's Shrine, Kochchikade. (4.8). You do not need the full tourist circuit. Pick two and commit.
Visa and entry
Colombo is US passports get visa on arrival. Check the embassy site before booking. The border process at CMB is standard. Budget 30 minutes.
How long do you need
The minimum useful layover is 4 hours. That gives you 40 minutes in each direction plus about 70 minutes on the ground. Up to 24 hours is a proper overnight.