Teobert Maler (1842-1917) is considered one of the most important expedition photographers of the 19th century. Between 1886 and 1910 he discovered and documented numerous Mayan ruins in the Yucatan Peninsula, which belongs to Mexico, and in the Peten region of Guatemala. Maler's 3,000 photographs, including unpublished original glass negatives from the holdings of the Ibero-American Institute, have been digitized and made available to researchers and the public.