[3] Sander's work includes landscape, nature, architecture, and street photography, but he is best known for his portraits, as exemplified by his series People of the 20th Century.

[4] Sander spent his military service (1897–1899) as an assistant to Georg Jung of Trier; they worked throughout Germany including in Berlin, Magdeburg, Halle, Leipzig and Dresden.

[4] Sander left Linz at the end of 1909 or 1910[4] and set up a new studio at Dürener Strasse 201 in the Lindenthal district of Cologne.

The series is divided into seven sections: The Farmer, The Skilled Tradesman, Woman, Classes and Professions, The Artists, The City, and The Last People (homeless persons, veterans, etc.).

[4] It contains a selection of 60 portraits from his series People of the 20th Century, and is introduced by an essay by Alfred Döblin titled "On Faces, Pictures, and their Truth".

[4] Around 1942, during World War II, he left Cologne and moved to the small village of Kuchhausen, in the Westerwald region; this allowed him to save the most important part of his body of work.

His Cologne studio was destroyed in a 1944 bombing raid, but tens of thousands of negatives, which he had left behind in a basement near his former apartment in the city, survived the war.

He also tried to record the mass rape of German women by Red Army soldiers in the Soviet occupation zone.

[10] In Wim Wenders' 1987 film Der Himmel über Berlin ("Wings of Desire"), the character Homer (played by Curt Bois) studies the portraits of People of the 20th Century (1980 edition) while visiting a library.

[12][13] In 1992, Gerd Sander, August's grandson, sold the archive to German nonprofit art foundation SK Stiftung Kultur.

[9] In 2017, Julian Sander, Gerd's son, claimed to represent August's estate, and issued a press release stating that the archive would now be housed by Hauser & Wirth.