In autumn 1955, a junior United States senator from Massachusetts came to Ireland on holiday. He was 38, recovering from back surgery, and not yet famous enough that his movements were public news. He came to Drumcondra to visit Father Joseph Leonard, a Vincentian priest at All Hallows whom he and his family had known for decades. Leonard had been spiritual director to the senator's late sister Kathleen, the one called Kick, who had married into the English aristocracy and died in a 1948 plane crash. At Leonard's invitation, John F. Kennedy gave an address to the All Hallows students. There is no surviving full text. There are letters in the college archive from Jackie Kennedy that the college tried to sell in 2014 to keep itself afloat - a sale that was eventually cancelled. Eight years after the visit Kennedy would return to Ireland as president; he would be dead within six months of that triumphant trip. The 1955 visit remained largely a private one, a young politician paying respects to a priest who had buried his sister.

The training programme took seven years. The first three concentrated on what the prospectus called physics, mental philosophy, languages, and English literature - a general humanities and natural sciences foundation that any nineteenth-century university would have recognised. The remaining four years were devoted exclusively to theology: sacred scripture, liturgy, canon law, church history, sacred eloquence, and dogmatic theology. The product was a priest equipped to walk into a parish in San Francisco or Sydney or Liverpool and conduct mass, hear confessions, baptise children, bury the dead, and preach in English to a congregation that probably already knew Irish English in their own families. The architect James Joseph McCarthy, designer of dozens of Irish Catholic churches, served as professor of ecclesiastical architecture, ensuring his graduates would understand the buildings they would administer. The composer Vincent O'Brien taught Gregorian chant from 1903, ensuring they could lead the music of the mass.

The Second Vatican Council, from 1962 to 1965, reshaped Catholic seminary education across the world. At All Hallows the change was visible within a decade. The college began admitting women from religious orders. It began admitting lay students. It started teaching adult education, certificates, diplomas, and degrees in theology, humanities, and pastoral studies. The seminary identity slowly faded. The final two ordinations took place in 1998; the college continued for another eighteen years as a humanities and theology institution, validated first by NCEA and then by Dublin City University, with about seven hundred students enrolled at its peak. Roughly half of every incoming undergraduate cohort were mature students aged twenty-three or over. The priest factory had become an unusually generous adult education college that retained an unmistakable Catholic ethos.

The financial model never quite worked after the seminary disappeared. The Irish state's Free Fees scheme capped how many students All Hallows could enrol, and the college received no direct state funding. A 2014 fundraising effort - including the proposed sale of Jackie Kennedy's letters to Father Leonard - was cancelled, and on 23 May 2014 the trustees announced that the college would wind down. The campus in Drumcondra was sold to Dublin City University in April 2016. The final graduation, on 1 November 2016, was presided over by the vice-president Mary McPhillips and the DCU president Brian MacCraith. The college formally closed on 30 November 2016. The buildings did not become apartments. DCU's School of Theology, Philosophy, and Music moved in. The Church of Ireland Centre moved in. The Jesuit Library from Milltown Park, 140,000 volumes of theology and philosophy, moved into Woodlock Hall on a ten-year loan. A primary school is planned for part of the grounds. Most of the college's degree programmes were transferred to other institutions and continue elsewhere. What ended was the institution; what continued was the work.

The campus is built around Drumcondra House, an early Georgian mansion the college absorbed when Hand bought the land. The Temple Folly, a small classical structure from 1720, is the oldest building on the site. Purcell House, originally called Junior House, was designed by the architect J. J. O'Callaghan in 1884. O'Donnell House opened in 1958. The chapel, with its organ built in 1898 by Telford and Telford of Dublin, has been used over the years by choirs and orchestras and once, in March 2016, hosted a recording of Enya singing for the BBC's Songs of Praise. In one corner of the grounds is a graveyard where John Hand is buried, alongside presidents, professors, and students of the college from across its 174 years. Around them, ancient trees commemorate other graduates and staff long dead, planted slowly over generations as a quieter, greener form of remembrance than the monuments inside the chapel.