Robot navigation in human spaces today largely relies on the construction of precise geometric maps and a global motion plan. In this work, we navigate with only local sensing by using available signage - as designed for humans - in human-made environments such as airports. We propose a formalization of "signage"and define 4 levels of signage that we call complete, fully-specified, consistent and valid. The signage formalization can be used on many space skeletonizations, but we specifically provide an approach for navigation on the medial axis. We prove that we can achieve global completeness guarantees without requiring a global map to plan. We validate with two sets of experiments: (1) with real-world airports and their real signs and (2) real New York City neighborhoods. In (1) we show we can use real-world airport signage to improve on a simple random-walk approach, and we explore augmenting signage to further explore signs' impact on trajectory length. In (2), we navigate in varied sized subsets of New York City to show that, since we only use local sensing, our approach scales linearly with trajectory length rather than freespace area.