Day 1, also known as Amazon Tower II and Rufus 2.0 Block 19, is a 521-foot-tall (159 m) office building in the Denny Triangle neighborhood of Seattle, Washington, located at the intersection of Lenora Street and 7th Avenue. It is part of the three-tower complex that serves as the headquarters of Amazon. The name "Day 1" previously belonged to two buildings on Amazon's South Lake Union campus, but both structures have since been renamed. The building's east facade features a large sign reading "Hello World". The construction project was the most expensive in the city to finish in 2016 amidst the recent downtown housing boom.