The oldest university is the University of Coimbra founded in 1290, and the biggest by number of enrolled students is the University of Porto with about 28,000 students. The Catholic University of Portugal, the oldest "non-state-run" university (concordat status), was instituted by decree of the Holy See and is recognized by the Portuguese State since 1971. The current public polytechnic subsystem was founded in the 1980s, but is an evolution of previous systems of higher vocational education that existed before. So, although only integrated in the system in the 1980s, several polytechnic institutions are much older, some having their origins back to the 19th century (examples are the "Instituto Superior de Engenharia de Lisboa", the " Instituto Superior de Engenharia do Porto" and the "Escola Superior Agrária de Coimbra").