Urban Economics - What's Your Vision From the Beginning?

When i was a gradti many years ago, i was interested in what economists call urban economics. And i wrote a theory paper on how the presence of local governments would lead to the over provision of goods with negative extrernalities. But it quickly became hopelessly difficult mathematically because people move around and that just makes the map almost impossible. I concluded that urban economics was a bad topic to research, and i moved on. Now at roughly the same time, you also started working in urban economics, and you looked at the problems in such a way that you almost single handedly brought urban economics from the periphyry of the profession to its con place of vibrancy.