Here we go. Straight from Wiki.
"The University is ranked 56th in the latest 2011 U.S. News and World Report rankings of "National Universities" across the United States, and it is ranked 18th nationally among public universities. 29 undergraduate and graduate programs are ranked in the top 10 and 90 programs are in the top 25.[49]
The Academic Ranking of World Universities compiled by the Shanghai Jiao Tong University ranked Maryland as 36th in the world as well as 8th among public flagship universities in the United States.[50] Newsweek ranked the University of Maryland as 45th in their ranking "global universities." The THE-QS World University Rankings ranked the University of Maryland 104 on its top 400 universities in the world in 2010.[51] In 2010 QS World University Rankings[52] ranked the university 104th overall in the world."
TL;DR:
So nationally, 56 overall but top 10 for a bunch of programs (including mine, I believe. Not sure), 36th worldwide from some study, 45th from another, and 104th from yours.