The heir to the Bolognese astronomical tradition is not the Bologna Astronomical Observatory but the University's Department of Astronomy, which houses the historical archives of the so called Specola of Bologna. The records relate to the scientific and administrative life of the institution, started in 1711 as the astronomical section of the Istituto delle Scienze, which was founded by Count Luigi Ferdinando Marsili.
The oldest records date back to 1679 and concern the planning of the tower which, under Eustachio Manfredi's direction, would become the main astronomical institute of the city. The Specola later followed the vicissitudes of the Istituto delle Scienze until its current incorporation into the University.
The archives are made of six series: astronomical and meteorological observations, observations made at the mosaic mirror telescope, 61 envelopes containing records sorted by Guido Horn d'Arturo, four envelopes marked A to D, containing documents found at later stages, and the Guido Horn d'Arturo's Fond, consisting of letters donated by the astronomer's heirs.
The 61 envelopes represent the archives'most extensive series, it maintains the original arrangement devised by Guido Horn d'Arturo. They contain, among others, a precious collection of letters, exchanged between the astronomers working in Bologna and scientists from all over the world: Gian Domenico Cassini, Paris M. Salvago, Luigi Ferdinando Marsili, Johann Jakob Scheuchzer, Antoine F. Laval, Ottaviano Fabrizio Mossotti and Guido Horn d'Arturo. The most recent documents date back to 1958.