We present empirical evidence that land values are scale free and introduce a network model that reproduces the observations. The network approach to urban modeling is based on the assumption that the market dynamics that generates land values can be represented as a growing scale-free network. Our results suggest that the network properties of trade between specialized activities cause land values, and likely also other observables such as population, to be power-law distributed. In addition to being an attractive avenue for further analytical inquiry, the network representation is also applicable to empirical data and is thereby attractive for predictive modeling.