Mary Markley Hall, at 1503 Washington Heights, is the largest of the Hill dorms, housing some 1,200 students, a large ResComp site, and both a cafeteria and a snack bar.
Since Markley is shaped like a letter "H", it gets mentioned whenever the "Jeanne Dixon predicted a massacre on Halloween in a dorm shaped like a letter" urban legend goes around.
Official UM page about Markley: http://www.housing.umich.edu/residencehalls/markley/