Campus map
There are a few campus maps of Gunn available online, though due to the recent construction few of them are both up-to-date and to-scale. Here are a few:
OSM
A map from OpenStreetMap, an open-source map which shows the outlines of Gunn's buildings and their letters, but not classroom numbers:
UGWA
A floor plan from UGWA, which is not up-to-date but is to scale and shows classrooms:
Official Gunn Website
This one is the official campus map, which is more-or-less up to date but has just awful dimensional accuracy.