Photo of the Vatican Necropolis from 1950. The first modern excavations under St. Peter’s Basilica began in the 1940s, under Pope Pius XII, with the goal of locating St. Peter’s tomb. Several ancient mausoleum’s were discovered, the earliest dating to 100 AD [779 x 1000]

Life magazine has more photos here: https://www.life.com/history/life-at-the-vatican-unearthing-history-beneath-st-peters/