Assas, as it is most commonly known, is the Panthéon-Assas University (Paris II). Assas is France's top university for Law, and well among the world's top universities in the same field.
Formerly part of the historical University of Paris - in which it was the Faculty of Law and Economics - Assas became an independent university in 1968, when, during a cultural revolution in Paris, several faculties seceded from their parent university. Each of these newly-founded independent universities was already specialised in a certain field, which led to each being renown for that particular field.
Assas shares its main building with Paris II, right in the heart of Paris, so the Parisian life is always an intricate part of students' life. However, it does have other campuses around Paris. Plus, all students under 25 have free entrance to all permanent exhibitions at Parisian museums, as well as reductions for most temporary exhibits and guided visits.
To get to Assas, just catch the metro to Cluny - La Sorbonne station, on line 10, or the RER to Luxembourg station. If you prefer the bus, just take one of these buses: 21, 27, 38, 63, 85, 86, 87.