Cities inspire us in so many ways. For architect Teddy Cruz, the contrasts between the sister cities of San Diego and Tijuana have inspired award-winning work that explores border crossings, reuse and adaptation of materials and buildings, and new patterns of mixed income housing. His firm, Estudio Teddy Cruz, has been working along the Mexican border for years. He won the 2004-2005 James Stirling prize for Border Postcard: Chronicles from the Edge, a project exploring new urban strategies for the international border zone spanning the two cities.

Jamie Wallace is a Pittsburgh attorney who found a different calling as owner of Abay, an Ethiopian restaurant in the city's East End. It's the first in a series of conversations with urban entrepreneurs who are changing neighborhoods in America's cities with their passion, their hard work and their investment.

This week Smart City takes a look at the contrasts from within and between our cities.