This is the oldest known photograph depicting the <a href="https://en.wikipedia.org/wiki/Grotto_of_Our_Lady_of_Lourdes,_Notre_Dame" class="extiw" title="en:Grotto of Our Lady of Lourdes, Notre Dame">Grotto at the University of Notre Dame</a>. This photograph, taken in 1896 shows the grotto at that time, along with a number of Holy Cross brothers and priests engaging in prayer.
Unknown author<span style="display: none;">Unknown author</span>
1896
University of Notre Dame archives