“The 99% Invisible City: A Field Guide to” by Roman Mars is a book published by Houghton Mifflin that explores the hidden aspects of cities. It offers insight into the intricate systems and infrastructure that make urban environments function. With a focus on free shipping and cost-saving tips, the book provides readers with practical advice while also shedding light on the complexities of city planning and urban design. Roman Mars serves as a knowledgeable guide on this fascinating journey through the unseen aspects of the city.