You can go to openstreetmap.org, select "export", and then "manually select a different area". Shift-drag the box to the size that you want. Don't click export - just use those numbers in `generate_tiles.py` (making sure that you've commented out any areas already in `generate_tiles.py`)`generate_tiles.py`). Another helpful site is [http://osm.duschmarke.de/bbox.html][1] - use alt-drag, and you'll see bbox examples suitable for lots of programs. [1]: http://osm.duschmarke.de/bbox.html

You can go to openstreetmap.org, select "export", and then "manually select a different area". Shift-drag the box to the size that you want. Don't click export - just use those numbers in `generate_tiles.py` (making sure that you've commented out any areas already in `generate_tiles.py`)