Cermáčí well near Dlouhomilov

There are places that are widely known, sought after by the entire nation and massively visited. And then there are places generally unknown, or known to natives and initiates. Fortunately, thanks to the digital age, it sometimes happens that someone carelessly mentions the unknown places and thus reveals the hidden destination even to the ignorant and uneducated.
That's probably how I was interested in the existence of a well while planning a bike ride...