Today is the Feast of St. Helen, the holy mother of the Roman Emperor Constantine I. She is best known for her discovery of the True Cross of Our Lord in Jerusalem. St. Helen helped establish notable Churches, such as that of the Holy Sepulchre in Jerusalem, but also brought many precious relics back to Rome. Tradition has it that she was born in Britain, and we know that she was espoused to the Emperor Constantius Chlorus.
St. Helen of Constantinople by Cima da Conegliano (1495AD)
You can read more about the life of St. Helen here: Old Catholic Encyclopedia: St. Helen
This site gives a short summary about today's saint with a few images and links: Catholic Saints Info: St. Helen
This page, while not exactly for the Feast of St. Helen, does discuss the finding of the Cross -- a feast once in early May, but later combined with that of September (the Sept. feast was inspired by the defeat of the Persians by the Emperor Heraclius and the recovery of the relics in the 7th century):
Fisheaters: Exaltation of the Holy Cross
The Basilica of Santa Croce in Gerusalemme in Rome.
["Santa croce di gerusalemme at Night" by Livioandronico2013 - Own work. Licensed under CC BY-SA 4.0 via Wikimedia Commons]
The Church of Santa Croce in Gerusalemme in Rome, just down the Via Carlo Felice from the Pope's Cathedral at San Giovanni in Laterano (St. John Lateran) in the southeast corner of the city, was built around a part of the palace of St. Helen. It was here that the relics brought back to the Eternal City by St. Helen were, and still are, housed for veneration. These include: part of the inscription, a nail, a couple of thorns, parts of the True Cross, the cross beam of the good thief’s cross, and the finger of St. Thomas. It is certainly well worth a visit!
Here is a link to the parish website: Basilica of Santa Croce in Gerusalemme, Roma