Paris

The city of Paris in the Girl Genius universe is, like our own, renowned as a place of art, music, and learning. It has been, and continues to be, a respite from the chaos that troubled the rest of Europe. Paris is not considered part of the Wulfenbach Empire, likely because it hasn't required the imposition of order from the Baron. Instead, Paris falls under the demesne of the Master of Paris, a particularly powerful Spark who does not appear to have ambitions much beyond keeping the city of Paris pleasant, beautiful, and safe.

In fact, Gil's overprotective father considered Paris safe enough for his own son, allowing him to live there on his own while he attended a university. (Although he was still unknown as the Baron's son at this point.) Gil has fond memories of Paris -- it's where he found inspiration for the music played by his Mechanical Orchestra. It's also where he found the Heterodyne Device, developed some sort of reputation with women, and made an enemy out of Othar Tryggvassen (but how hard is that?).