Cascade is an urban neighborhood abutting Downtown Seattle, Washington, United States, located adjacent to South Lake Union. It is bounded by: Fairview Avenue North on the west, beyond which is the rest of the Cascade Neighborhood; the Interstate 5 interchange for Mercer St to the north, beyond which is Eastlake; Interstate 5 on the east, beyo…Cascade is an urban neighborhood abutting Downtown Seattle, Washington, United States, located adjacent to South Lake Union. It is bounded by: Fairview Avenue North on the west, beyond which is the rest of the Cascade Neighborhood; the Interstate 5 interchange for Mercer St to the north, beyond which is Eastlake; Interstate 5 on the east, beyond which is Capitol Hill; and Denny Way on the south, beyond which is Denny Triangle. It is surrounded by thoroughfares Mercer Street, Fairview Avenue N. and Eastlake Avenue E., and Denny Way. The neighborhood, one of Seattle's oldest, originally extended much further: west to Terry Avenue, south to Denny Hill on the South, and east to Melrose Avenue E through the area now obliterated by Interstate 5. Some recent writers consider Cascade to omit the northern "arm", while others extend it westward to cover most of South Lake Union.