Joseph Stübben initially published City Building (Der Städtebau) in German in 1890 as part of a handbook on architecture (Handbuch der Architektur). This Handbook was published in Germany by Durm et al. (1890) between 1883-1933. Stübben subsequently published revised versions of Der Städtebau in the 1907 and 1924 editions of the handbook. The 1890 edition is still published in Germany as a reprint. In 1911 Adalbert Albrecht translated the 1907 edition of Der Städtebau into English. This translation is available as a typescript at the Frances Loeb Library at Harvard University. It contains all chapters except for Part V. More about the translation here.
Forward by Emily Talen and Julia Koschinsky
You can download the complete book here.
Or download individual sections:
Part 1: The fundamentals of city-building
Part 2: Component parts of the city building plan
Part 3: The complete plan
Part 4: The execution of the city plan
Part 6: City planted areas