Thomas Pelham, the Chief Secretary for Ireland, introduced the bill in 1795. The new college was to provide "for the better education of persons professing the popish or Roman Catholic religion," with room for up to five hundred seminarians and the ordination of as many as ninety priests each year. The motive was strategic. Until the Roman Catholic Relief Act of 1793, Catholic priests had been trained on the European mainland, principally in France, Spain and the Low Countries. The French Revolution had made every Irish priest returning from Paris a potential carrier of revolutionary ideas. Several of the first professors at Maynooth were themselves French refugees from the Terror, sometimes called the French founding fathers: Anglade, Darré, Delahogue and Delort. Edmund Burke recommended a layman, James Bernard Clinch, for an early teaching post. The first ordinations from Maynooth took place in 1800. By 1845, when the British government tripled the Maynooth grant, the college had become one of the great institutions of Irish Catholic life.

In 1896 Pope Leo XIII granted the Pontifical Charter, giving the college the right to confer its own degrees in canon law, philosophy and theology - degrees the Royal University of Ireland was not permitted to award. The same period produced the most precious building on the campus: the College Chapel. Its foundation stone was laid in 1875, and it was opened for worship in 1891 to mark the run-up to the college's centenary. The chapel sits at the end of St Joseph's Square, a formal garden flanked by Callan Hall and Physics Hall on the east and Dunboyne House on the south. The buildings carry the dignity of an enclosed Catholic world: the staff dining hall, the museum, the John Paul II Library opened in 1983 to mark Pope John Paul II's 1979 visit to Maynooth. Stoyte House, the oldest on the south campus, dates from 1780 and was originally home to the steward of the Leinster estate.

Among the priests who taught at Maynooth in the nineteenth century, none was stranger or more consequential than Nicholas Callan, professor of natural philosophy. Working in a laboratory in the college, Callan invented the induction coil in 1836 - the device that made it possible to step up low voltages into high voltages, foundational to everything from automobile ignition systems to early radio transmitters. He also built what came to be called the Maynooth Battery. His apparatus is preserved in the National Science Museum on the college grounds, alongside instruments associated with Marconi. Callan himself is buried in the campus. The museum, established formally in 1934, holds the ecclesiastical artifacts you would expect of a great seminary - vestments, chalices, illuminated manuscripts - and the surprising scientific instruments of a priest who happened to be one of the most important electrical engineers of the nineteenth century.

When the Universities Act of 1997 transferred the secular faculties of arts, science, Celtic studies and philosophy to the new Maynooth University, St Patrick's remained as a separate legal entity, focused on its original mission of theological education. The two institutions share a campus but pursue different work. The Pontifical University trains Catholic seminarians and lay students of theology, awards pontifical degrees in canon law, philosophy and theology, and serves as a centre for Catholic scholarship in Ireland. The current president, Reverend Michael Mullaney, took office on 1 September 2017. Walk through the cloisters and St Joseph's Square on a quiet afternoon and you walk through 230 years of one continuous Irish institution - founded by people frightened of the French Revolution, sustained by generations of priests, and still here, in a country that has changed almost beyond recognition around it.