SR 99/SR 599, parts of which are also known as West Marginal Way, begins in Tukwila at I-5 and continues north to the First Avenue South Bridge, where it interchanges with SR 509, then continues as a surface street (East Marginal Way) for a few miles, then, adjacent to CenturyLink Field, becomes the SR 99 Tunnel. This tunnel passes under downtown Seattle and emerges in South Lake Union as Aurora Avenue, a divided expressway (partial control of access with interchanges) until Green Lake, where it becomes a surface street again. SR 599 was built in 1968, the freeway portion of SR 99 was built in 1956 as was the First Avenue South Bridge (a second structure was built next to the first in the early 1990s), and the Alaskan Way Viaduct was open in 1952, with an extension open in 1959, until its closure and demolition in 2019. North of that, Aurora Avenue was built in 1932, including the cantilever/truss George Washington Memorial Bridge.