Duquesne University comprises Census Tract 103 (data from the 2010 Decennial Census, map generated using TIGERweb).
A Census Tract is a "small, relatively permanent statistical subdivisions of a county or equivalent entity." Although census tracts may not correspond directly to geographically demarcated neighborhoods, these divisions attempt to capture smaller population sizes ("between 1,200 and 8,000 people, with an optimum size of 4,000 people"). See "Geographic Terms and Concepts - Census Tract" from the U.S. Census Bureau for more information.
Duquesne University contains Block Groups 2, 3, and 4...
...which in turn contain a number of individual blocks (data from the 2010 Decennial Census, map generated using TIGERweb).
Block Groups are composed of "clusters of blocks within the same census tract that have the same first digit of their four-digit census block number." See "Geographic Terms and Concepts - Block Groups" from the U.S. Census Bureau for more information.
Small geographic entities such as Census Tracts, Block Groups, and Blocks (or, in some cities, Block Numbering Areas) were implemented in various ways over time (see "Tracts and Block Numbering Areas" from the U.S. Census Bureau for a more detailed history). You may find that these entities remain consistent for the area you are studying over time. However, you might also discover that your area of focus contains boundaries that changed over time, or that it was subdivided into smaller geographic entities.