Every town should have a flea market. This one in Prague is relatively new and does not have the popularity of the flea markets in Amsterdam or Lisbon. However, as in any flea market, you never know what you will find. It is claimed to be “probably the largest flea market in Europe”.
This market is extremely well organized and runs like clockwork. All the details about the fees and spaces can be found on their website (in English).
So, if you want to find something from the recent past, or the communist regime, or from the time when Czechs lived in the Austro-Hungarian empire, there is a pretty good chance that it will be hidden here in the middle of other junk and you can get it for close to nothing. And, if you came with too much of your own stuff, you can sell it right here – renting a spot for selling costs about 5 euros.