And besides the official from Prague, I received also some other Unesco cards. This first one was sent by Postcrossing "mother" Ana. She sent me this beautiful card from Suzhou Gardens, Unesco site since 1997.
This one was sent by ElSol, from one group of Castles RR. It shows the Mikhailovsky Castle in Saint Petersburg historic center.
This last one was sent by Sania from Canada, and it shows the Canadian Rockies.