The Museum, of contemporary design, houses rare stamps depicting the Principality’s postal history, as well as all the documents which have been used in the stamp-printing process from the first Charles III stamp in 1885 to the present day.
The Museum of Philately and Coinage is open daily from 10 am to 5 pm (6 pm in July and August). It sells currently available stamps and coins issued by the Principality.
https://www.visitmonaco.com/us/place/museums/90/museum-of-stamps-and-coins