The State Route 99 tunnel runs under Belltown for a number of blocks as it connects the Alaskan Freeway to Aurora Avenue North.- Belltown is the most densely populated neighborhood in Seattle, Washington, United States, located on the city’s downtown waterfront on land that was artificially flattened as part of a regrading project. Formerly a low-rent, semi-industrial arts district, in recent decades it has transformed into a neighborhood of trendy restaurants, boutiques, nightclubs, and residential towers as well as warehouses and art galleries. The area is named after William Nathaniel Bell, on whose land claim the neighborhood was built.