Whether buildings can actually quote or not other buildings (like a text would do) isn't really the question here. I think we can all agree that references to other projects, styles or architects are a pretty common thing, even when they're not quite acknowledged by the architect himself. It was actually (to me atleast) one of the few bright spots of postmodern architecture.
So anyway, let's see what we can come up with! I'll start with a couple of easy ones.
Philip Johnson -
Gerald D. Hines College of Architecture, University of Houston (1985)
[url]http://www.pritzkerprize.com/sites/default
Claude-Nicolas Ledoux,
House of Education (project), 1773-1779
http://rubens.anu.edu.au/htdocs/laserdisk/0244/24452.JPG
James Stirling,
Engineering Building - Leicester University, 1959
http://quintinlake.files.wordpress.com/2010/03/leicester-engineering-building-james-stirling-17.jpg?w=500&h=766
Konstantin Melnikov,
Rusakov Club, 1927-29
http://2.bp.blogspot.com/-qukqnTo2uYc/TgYJj2etSZI/AAAAAAAAI_k/K91nP_je198/s1600/konstantin-melnikov-klub-rusalkovovd18dch-zd0b1vodov-1928.jpg