South Lake Union is a neighborhood in central Seattle, Washington, so named because it is at the southern tip of Lake Union. The official boundaries of the City of Seattle Urban Center are Denny Way on the south, beyond which is Denny Triangle; Interstate 5 on the east, beyond which is Capitol Hill; Aurora Avenue N. and 7th Avenue N. on the we…South Lake Union is a neighborhood in central Seattle, Washington, so named because it is at the southern tip of Lake Union. The official boundaries of the City of Seattle Urban Center are Denny Way on the south, beyond which is Denny Triangle; Interstate 5 on the east, beyond which is Capitol Hill; Aurora Avenue N. and 7th Avenue N. on the west, beyond which is Lower Queen Anne; and Galer Street, Lake Union, and E. Newton Place on the north, beyond which are Westlake and Eastlake, but like most Seattle neighborhoods, its precise boundaries are indeterminate. In particular Cornish College of the Arts and Vulcan Inc. properties such as 2200 and 2201 Westlake are officially in Denny Triangle for city planning and zoning purposes but often referred to as South Lake Union. The portion of South Lake Union east of Fairview Avenue N. is historically known as Cascade. Historic structures continue to stand in the Cascade neighborhood today.