Delivered three times between 1898 and 1902 and subsequently revised with an eye toward publication, Alois Riegl's lectures on the origins of Baroque art in Rome broke new ground in its field. In his approach and content, Riegl offered a markedly different account from that of Heinrich Woelfflin and other contemporaries: the beginning of the new artistic era extending from the 1520s to the seventeenth and eighteenth centuries was to be judged by its own rules and not merely as a period of decline. This first English translation brings Riegl's compelling vision of the Baroque to life and amply illustrates his charisma as a lecturer. His text is full of perceptive observations on the most important artists of the period from Michelangelo to Caravaggio. By taking the spectator into consideration, Riegl identifies a crucial defining change between Renaissance and Baroque art and provides invaluable inspiration for present-day readers.