St. Agnes has been the subject of great sermons and poetry down through the ages (not to mention a major character in Cardinal Wiseman’s novel Fabiola). An excellent book about here is available online: Life of St. Agnes, Virgin and Martyr by Aloysius Smith.
Here is a little from the introduction:
SAINT AGNESE FUORI LE MURA was in a ferment of excitement on the afternoon of Monday, November 25, 1901. News had reached the abbey that an important discovery might be made at any moment in the adjoining basilica. For many years the inmates of St. Agnes’s Abbey had desired to ascertain the exact spot where the relics of their beloved patroness had been deposited. But two revolutions, the French and the Italian, had utterly ruined the religious, and put
it out of their power to undertake the necessary excavations.
Catholic Germany came to the aid of the Koman Canons Regular. Cardinal Kopp, Prince-Bishop of Breslau, was created in 1893 a cardinal priest of the title of St. Agnes on the Nomentan Way. From the day when his Eminence took possession of his titular Church he graciously evinced a friendly and lively interest in the Order to which its clergy belong. Thanks to the Cardinal s generosity, the Canons were enabled to gratify their pious curiosity in respect to the Roman martyr’s resting-place.
Excavations were begun in October, 1901. The sanctuary of the ancient and beautiful basilica was selected for the field of operations, which were super intended by Monsignor Wilpert and Dom Augustus Bacci, C.R.L. The pavement behind the high altar covering, what is known as the retro sanctos, or vicinity of the saints, was broken through, and a long and careful search was made, with interesting results. At a depth of nearly 5 feet a gallery was discovered running parallel with the altar, containing arcosolia
and intact graves of Christians who had been buried as close as possible to the virgin martyr’s remains. Coins were found of the fourth and fifth centuries, and inscriptions of a great historical and archaeological value were brought to light.
The story of St. Agnes in the book Fabiola takes many liberties, but still ends with her martyrdom and internment in the catacombs that now bear her name. While there have been at least 3 movies made based on the book, only one contains the martyrdom of St. Agnes (as described in the book) and the internment in the catacombs: the first one from 1918 (scenes at the end of the movie).