Westlake Center, in two parts

Westlake Center was built in 1988, largely on the path of Westlake Ave (a diagonal street that shoots from the west side of Lake Union right into the middle of downtown in an awkward way) and the site of the original downtown Monorail station, and includes both the mall and the office tower (though they aren't integrated in any meaningful way). This side of the mall was remodeled in the 2010s, but the rest of the mall doesn't seem to have seen much change over the years (sadly, all that means is that the extremely boring design has stayed as is).