Widely regarded as the most important metal and glass structure of the 19th century, the Palais des Machines was widely admired at the time of its inauguration at the Paris Universal Exhibition of 1889. Although extremely influential in first half of the 20th century (impressing Behrens and Gropius among others), it subsequently came to represent little more than a footnote in modernist histories. This work seeks to re-establish the building's true significance, demonstrating the Palais's interaction between the thinking of the Ecole des Beaux-Arts and innovative approaches towards technology of the era. Each of these monographs is designed to be a complete and accurate archival record, aiming to become a standard reference on that building, for students and scholars as well as practising architects.