The Büyük Yeni Han (I often write Yeni Büyük) was built in 1764 (much later than the other big han, the Valide, which is from 1651). And for being big. The Valide beats it again in size.
It has been divided in the middle by a 19th century construction, diminishing its length (but convenient as a shortcut). The han itself was built by Sultan Mustafa III and is one of the best extant examples of the baroque han.