For designers, attempting to respond to unknown design spaces can be a daunting task. This paper describes a series of workshops that presented rapid ethnographic design methods in city streets as a way of exploring human behaviours, and recording their traces. One instance of the workshop is described in detail to highlight the connections between the data gathering and the concept generation phases. Emphasis was placed on discovering “bleed points” where the virtual world can connect with the physical world. This activity was carried out with the aim of considering possibilities for interaction scenarios in future urban settings. The ethnographic observation and data gathering process itself was paramount in these workshops, enabling designers to engage with existing and potential interaction situations. Early concept development was the endpoint of this process, and designed responses were developed primarily to describe the emergent urban design space, rather than as a step towards any finished system or product.