Hello from Poland!
Cześć! That's awesome! Częstochowa is the city in which the well-known Jasna Gora Monastery is located, if it helps you remember. Personally, I still have yet to visit Łódź, so you're ahead of me on that one!
Oh yes, then we did go there, too! I remember going to the Monastery and seeing the Black Madonna.
And I echo what was said above - people use pinpics to trade, but a lot of people use it as just a database of pins in their collection, too. I do a little trading through it, but I mostly use it to keep track of what I have and what I'm looking for. I collect Lion King, and there are so many pins overall and so many that are similar to each other that it's impossible to remember everything. I love having the database that I can reference for my collection.