Gioacchino Ersoch served the city of Rome from 1848 to 1889, in the crucial step of the capital cities of the Papal States to the capital of Italy. A period that resulted in decisive transformations not only for political and social affairs, but also to the urban and architectural history of the city. Ersoch tried to interpret these changes providing proposals and concrete answers to the changing needs of a modern metropolis. But Ersoch is above all the "great inventor" of new slaugherhouse in the Testaccio district of Rome. In addition to essays dedicated to various aspects of the work of Ersoch, the original designs found, the volume also offers a complete list of his projects and his works never published previously.