You've probably heard of Rome's Christian catacombs, but many visitors to the eternal city haven't yet discovered their older counterparts: the Jewish catacombs of Villa Torlonia. That's partly because they're not open to the general public.

That changes on September 5. Rome is opening the catacombs, which boast Jewish frescoes and tombs from the 2nd to 5th centuries AD, to visitors — for one day only. It's part of the city's participation in the annual European Day of Jewish Culture, celebrated by more than 25 countries. The free guided tours of the catacombs are available on the hour, all day.

Interested? Book now. Even though the announcement appears to be so new that those working Rome's main telephone line for cultural events and reservations hadn't even heard of it yet, most of the tours have already been booked up — leaving only those at 1pm, 2pm and 3pm. Call +39 3407368280 to book.

For more information about Villa Torlonia (in Italian), click here. For a map, click here. Hat tip: Katie Parla.