Oslo-Gardermoen International Airport — Oslo (Gardermoen), Norway

When OSL opened at Gardermoen in 1998, it replaced the cramped, centrally located Fornebu field and gave Norway's capital an airport built for long-term growth, roughly 35 miles north of the city but linked to it by the high-speed Flytoget train in under 25 minutes. It has since grown into the primary hub for both Norwegian Air Shuttle and SAS, anchoring domestic routes across a country where mountainous terrain often makes flying more practical than driving, alongside long-haul connections to North America and Asia. Gardermoen has also become a reference point for sustainable aviation efforts, incorporating extensive use of timber in its terminal expansion and backing early initiatives around biofuel and electric aircraft infrastructure. As Norway's busiest airport by a wide margin, it dwarfs Bergen and Stavanger in traffic and functions as the country's principal connection to the rest of the world.