Does anyone send postcards anymore?  Some people still do.  Postage stamps can usually be purchased in the store that sells postcards. If not, most hotels sell them as well. The post offices (Česká pošta) are located throughout town. The main post office, open 22 hours per day (cleaning the remaining 2 hours I guess :-), is in Jindřišská street, just off the Wenceslav Square. The price depends on where you are sending the card to and its size.