“The trickiest part is turning it on,” Paul Jacobs said one night recently as he took his seat at the console of the organ at St. Patrick’s Cathedral for the first time. Ah, the plight of the itinerant organist. Where, amid the myriad buttons and knobs and levers and (literal) bells and whistles, was the on-off switch?

“It’s like sitting in the cockpit of a Boeing 767,” he said. “But with the controls in a different place every time.”

Mr. Jacobs, the boyish-looking 38-year-old chairman of the organ department at the Juilliard School and a well-traveled concert performer in his own right, was giving a private tour of some of New York’s finest organs, including those of the Church of St. Ignatius Loyola on Park Avenue and the Church of St. Mary the Virgin, near Times Square. (St. Patrick’s and St. Ignatius are Roman Catholic, St. Mary Episcopalian.) The idea for the tour grew out of conversations over several years, in which Mr. Jacobs, originally from Washington, Pa., near Pittsburgh, spoke glowingly of the wealth of pipe organs in New York and of the qualities — the personalities, if you will — of specific instruments.

And what better stop for a musical tourist than St. Patrick’s on Fifth Avenue — just opposite the secular tourist mecca of Rockefeller Center — with its mighty organ? The instrument, made by the Kilgen firm in St. Louis and installed in 1930, boasts five keyboards (called manuals on an organ, to distinguish them from the pedalboard, which is the row of keys played by the feet), hundreds of stops (those knobs that determine which ranks of pipes will come into play in which combinations, and thus which timbres will result) and thousands of pipes, large and small.