Useful info
The schedules:
> from August 31 to November 1, 2020: from 11 am to 5 pm (last visit) - without interruption at lunchtime
CLOSED ON MONDAYS - EXCEPT DURING THE ALL SAINTS' DAY HOLIDAYS
> from 2 November to 29 November: from 11 am to 4 pm (last visit) - without interruption at lunchtime.
Open on all public holidays.
Automatic departures every 12 minutes (per group of 15 people max.)

Temperature underground:
12°C
Warm clothing and closed shoes are recommended ...
Especially in case of high outside temperature !!!