Historically GÃ rlitz has belonged at times to the regions of Lusatia and Silesia .
It is opposite the Polish town of Zgorzelec , which was a part of GÃ rlitz until 1945 . Historically , GÃ rlitz was in the region of Upper Lusatia , however in 1815 , some parts of Lusatia were integrated into the Province of Silesia , and later into the Province of Lower Silesia .