Cities in the distant past-as documented by archaeologists and historians-provide an extensive record of urban successes and failures, yet this information has had little impact on the field of sustainability science. I explore two reasons for this situation. First, these scholars have often failed to synthesize their data scientifically, and, second, they have not approached the transfer of past knowledge to present research in a rigorous manner. I organize discussion these issues around three arguments for the present value of past cities: the urban trajectory argument, the sample size argument, and the laboratory argument.