This cache is on the route of the excursion described in old polish travel guide "12 trips to places near Warsaw" dated 1953. However, those places still exist, they are no longer near Warsaw, but are a part of the city, some even belong to the city center.
Here is a travel guide with description of that trip (in polish, you don't need to read it to find the cache).
The cache hidden near Królikarnia Palace, as 50 years ago we can get there by tram (18, 19, 36) or by bus (505, 524).