Toledo, sometimes known as "The Glass City", is the fourth largest city in Ohio.  Toledo is known as the Glass City because of its long history of innovation in all aspects of the glass industry: windows, bottles, windshields, construction materials, and glass art, of which the Toledo Museum of Art has a large collection.  Toledo had also been known as "The Auto Parts Capital of the World". Several large, Fortune 500 automotive related companies had their headquarters in Toledo.  The University of Toledo and Bowling Green State University are two of the citys larger secondary education institutions.  The Toledo Zoo is a highly rated zoo that is generally considered to be in the top ten in the United States.