Yosemite by Carleton Watkins

At the Metropolitan Museum in NYC, this was a modest but inspirational exhibition of Carleton Watkins' large-format photographs of Yosemite Valley in California (the link has all the images). Watkins (1829–1916) took them in the early 1860s; within a few years they made him nationally known, and in June 1864, with the Civil War still raging, President Abraham Lincoln decreed that the Valley would hence henceforth remain untouched ("inalienable"); that was the origin of our system of National Parks. Given that--and Watkins' fame otherwise--I suspect that he may be the single most influential photographer ever.

It was a relatively brief visit to the Met; there's also a one-room show of Thomas Struth's photographs. I plagiarized his image of San Zaccharia in Venice in 2011 here (the link has more information about him). The afternoon was mainly at the Guggenheim Museum, with a mammoth show of ZERO--an abstract art movement in Europe in the 1950s and '60s. (The link has a video of the best thing in the show--a small room with moving light sculptures).