3 Best Sights in O'Connell Street and Around, Dublin

Built on the profits of sin—well, by a generous wine merchant actually—and topped with a soaring Gothic spire, this church anchors the northeast corner of Parnell Square, an area that was the city's most fashionable address during the gilded days of the 18th-century Ascendancy. Popularly known as Findlater's Church, after the merchant Alex Findlater, the church was completed in 1864 with an interior that has a stark Presbyterian mood despite stained-glass windows and ornate pews. For a bird's-eye view of the area, climb the small staircase that leads to the balcony.

One of the city's finest churches in the classical style, the Jesuit St. Francis Xavier's was begun in 1829, the year of Catholic Emancipation, and was completed three years later. The building is designed in the shape of a Latin cross, with a distinctive Ionic portico and an unusual coffered ceiling. The striking, faux-marble high altarpiece, decorated with lapis lazuli, came from Italy. The church appears in James Joyce's story "Grace."

Dublin's principal Catholic cathedral (also known as St. Mary's) is a great place to hear the best Irish male voices: a Palestrina choir, in which the great Irish tenor John McCormack began his career, sings in Latin here every Sunday morning at 11 am. The cathedral, built between 1816 and 1825, has a classical church design—on a suitably epic scale. The church's facade, with a six-Doric-pillared portico, is based on the Temple of Theseus in Athens; the interior is modeled after the Grecian-Doric style of St. Philippe du Roule in Paris. But the building was never granted full cathedral status, nor has the identity of its architect ever been discovered; the only clue to its creation is in the church ledger, which lists a "Mr. P." as the builder.