This ambitious and beautiful historical pageant, aimed at children aged nine to 14, is set in the heady days leading up to the premiere of Handel's Messiah in the titular city and year. We first encounter its cast of real-life characters in a delightful series of tableaux set in nooks and crannies of the Ark building, which is done up to represent various buildings around the city. David Garrick and Peg Woffington rehearse a showy Hamlet in Smock Alley Theatre; an aged and evidently dotty Jonathan Swift squints over a manuscript in the Deanery of St Patrick's Cathedral; and Handel tinkers on a harpsichord in his Music Room.

Upstairs in the Ark rehearsal room, we discover the gossipy Laetitia Pilkington, the socialite and memoirist whose writings provide one of the main accounts of Swift's later years. She tells us about all the figures we've just met, setting up the production's central event: an hour-long play dramatising Handel's attempts to persuade Swift to loan him six boy singers from St Patrick's choir for the premiere. The writer, John Banville, cleverly has Pilkington control the play's action - she flits from a writing table at the side of the stage into the play-within-a play, narrating scenes and talking directly to the audience.

Overall, Banville sets the beam high: the characters use heightened language and convey complex ideas. At one point there is a discussion of Bishop George Berkeley's theories of matter and existence. But this doesn't seem to faze the young audience, who get caught up in the life and colour swirling around the simple plot - much of it provided by Monica Frawley's fantastically exaggerated costumes. One dress is made completely of pink feather boas; a birdcage-shaped hat comes complete with toy bird.

Eric Fraad's production is at its best when he departs from naturalism. Four characters enact the chaos of Handel's environment by speaking an overlapping fugue of Shakespearian dialogue, and at one point a pulpit swivels around to reveal sad old Swift dozing inside. There is some sloppy excess movement, however, and there are lost opportunities for pageantry between scenes - I longed for a few more snatches of Liz Roche's fine choreography to cover set shifts.

Among the strong cast, Michael Fitzgerald impresses particularly as a basso profundo Garrick, and Carmel Stephens ably holds the action together as Pilkington.

· In rep until June 30. Box office: 00353 1 670 7788.