The ETH Bibliothek in Zurich now has a large online collection of images as well as some special thematic collections at www.explora.ethz.ch

These include one on scientific illustration, see https://www.explora.ethz.ch/en/s/mallow-iris-orchid/  as well as a new one on marble’s use in architecture

https://www.explora.ethz.ch/en/s/marble-architecture-power/   as well as an older one on data degradation: https://www.explora.ethz.ch/en/s/surfing-the-sea-of-data/

 

Well worth exploring and all freely available!