If you do go there
Go to the theatre Piwnica at old Leszno 13. Here is a funny blog, Harry. A guy from Brooklyn searches his roots:
"13 Lesnow Street, Warszawa" was the address my ancestors gave to the authorities at Ellis Island when they arrived. I decifered the address to be Leszno Street 13.
So he goes there.
I learned a few days later while on the internet in a hotel in Wroclaw that 13 Leszno is a famous address, which explains while it was totally desimated and no longer exists