On the building called a PASTA skyscraper.
It was erected in 1904-1910 to become the first skyscraper in Warsaw. In 1922, it became the property of PASTA, i.e. the Polish Telephone Company of Shareholders.
During the Warsaw Uprising, on August 20, 1944, after bitter battles, the soldiers of the batallion �Kilinski� seized the PASTA Building from Germans. It was seriously damaged, but rebuilt after war.
The flags bear the symbol of "Anchor", which was a World War II emblem of the Polish Secret State and Armia Krajowa (Home Army, or AK) and became one of the symbols of the Warsaw Uprising. The same big symbol is placed on the roof.
http://en.wikipedia.org/wiki/Kotwica