| Montarrenti observatory | Sovicille | — |
| Monte Argentario observatory | Monte Argentario | — |
| Monte Autore observatory | Monte Autore | — |
| Monte Baldo observatory | Ferrara di Monte Baldo | 1.220 m |
| Monte Bianco obsertatory | Chamonix-Mont-Blanc | 4.807 m |
 Monte Mario Observatory | Roma | 128 m |
 Monte Viseggi Observatory | La Spezia | 347 m |
| Montevenere observatory | Monzuno | — |
| Monteviasco Astronomical Observatory | Curiglia con Monteviasco | — |
| Mount Matajur observatory | Savogna | — |
 Mt Etna Volcano Observatory | — | 2.940 m |
 Museo La Specola | Padua | — |
| Nastro Verde observatory | Priora | — |
 National Institute of Geophysics and Volcanology | — | — |
| New Millennium Observatory | Mozzate | — |
 Noto Radio Observatory | Noto | — |
| Nova Milanese observatory | Nova Milanese | — |
| Novi Ligure observatory | Novi Ligure | — |
| OACL observatory | Teramo | — |
| ObsCT observatory | Catania | — |
 Observatorio Astrofísico de Arcetri | Florencia | — |
 Observatorio Astrofísico de Asiago | Asiago | 1.045 m |
 Observatorio astrofísico de Turín | Pino Torinese | — |
 Observatorio Astronómico de Brera | Milán | — |
 Observatorio Astronómico de Cagliari | Cagliari | — |
 Observatorio Astronómico de Capodimonte | Nápoles | 150 m |
 Observatorio Astronómico de las Montañas de Pistoia | San Marcello Piteglio | — |
 Observatorio Astronómico de Merate | Merate | 362 m |
 Observatorio Astronómico de Palermo | Palermo | — |
| Observatorio astronómico Galileo Galilei | Suno | — |
 Observatorio astronómico Santa Lucia di Stroncone | Stroncone | 350 m |
 Observatorio Astronómico Sormano | Sormano | 1.128 m |
| Observatorio de aves de Capri | Anacapri | — |
| Observatorio de Colleverde | Guidonia Montecelio | 120 m |
| Observatorio de Monte Agliale | Borgo a Mozzano | — |
| Observatorio de Pianoro | Pianoro | — |
 Observatorio de Roma | Roma | 401 m |
 Observatorio San Vittore | Bolonia | 280 m |
 Observatorio Vesubiano | — | — |
| Observatory of San Vito a Montelupo | Montelupo Fiorentino | 100 m |
 Observatory of the Collegio Romano | Roma | — |
 Observatory TT1 | Castelgrande | — |
| OmegaLab observatory | Palermo | — |
 Orioloromano Observatory | Oriolo Romano | 400 m |
| Ornithological Observatory of Arosio | Arosio | — |
| Osservatorio Antonio Grosso | Brugherio | — |
| Osservatorio Astronomico | Piobbico | — |
| Osservatorio Astronomico Armenzano | Perugia | — |