The Florida highway through the Keys dates to the 1930s and the NYC Catskill aqueduct to roughly 1916 - those are certainly great projects but aren't the last fifty.
Largely agree with the rest of your comment though :)
Also, the highway through the Keys has seen very large infrastructure improvements over the last few decades, so while not a new project it is a significant civil engineering effort.
Largely agree with the rest of your comment though :)