This is a domestic card with extensive captioning in Czech, including this: Navštivte Muzeum čs. opevnění 1938 – Klášter II, which means something like: Visit the Museum MS. fortification 1938 – Abbey II.  The writer of the message on the card (mailed in 2012, two stamps, partial postmark) tried to explain everything, and probably did, if we have the patience.  Grade: 1