The Escuela Nacional Preparatoria (English: National Preparatory High School) (ENP), the oldest senior High School system in Mexico, belonging to the National Autonomous University of Mexico (UNAM), opened its doors on February 1, 1868.

[2] In 1867, Benito Juárez began reform of the educational system, taking it out of clerical hands and making it a government function.

San Ildefonso was converted into the Escuela Nacional Preparatoria initially directed by Gabino Barreda, who organized the new school on the Positivist model of Auguste Comte (Comtism).

[3] The complex remained a separate entity until 1929, when the Universidad Nacional gained autonomy, meaning it became independent of the government, though still government-sponsored.

Its present director is Luis Samuel Saloma, who made a tour along the 9 schools of the ENP, giving a final concert at the Auditorium at the General Direction.