Neil Jordan's film Michael Collins captured Dublin Castle's near indomitable status well: seat and symbol of the British rule of Ireland for more than seven centuries, the castle figured largely in Ireland's turbulent history early in the 20th century. It's now mainly used for Irish and EU governmental purposes. The sprawling Great Courtyard is the reputed site of the Black Pool (Dubh Linn, pronounced dove-lin) from which Dublin got its name. In the Lower Castle Yard, the Record Tower, the earliest of several towers on the site, is the largest remaining relic of the original Norman buildings, built by King John between 1208 and 1220. The clock tower building now houses the Chester Beatty Library. Guided tours are available of the principal State Apartments (on the southern side of the Upper Castle Yard), formerly the residence of the English viceroys and now used by the president of Ireland to host visiting heads of state and EU ministers. The State Apartments are lavishly furnished with rich Donegal carpets and illuminated by Waterford glass chandeliers. The largest and most impressive of these chambers, St. Patrick's Hall, with its gilt pillars and painted ceiling, is used for the inauguration of Irish presidents. The Round Drawing Room, in Bermingham Tower, dates from 1411 and was rebuilt in 1777; numerous Irish leaders were imprisoned in the tower from the 16th century to the early 20th century. The blue oval Wedgwood Room contains Chippendale chairs and a marble fireplace. The Castle Vaults now hold an elegant little patisserie and bistro.

Carved oak panels and stained glass depicting viceroys' coats of arms grace the interior of the Church of the Holy Trinity (formerly called Chapel Royal), on the castle grounds. The church was designed in 1814 by Francis Johnston, who also designed the original General Post Office building on O'Connell Street. Once you're inside, look up -- you'll see an elaborate array of fan vaults on the ceiling. More than 100 carved heads adorn the walls outside: among them, St. Peter and Jonathan Swift preside over the north door, St. Patrick and Brian Boru over the east.

One-hour guided tours of the castle are available every half hour, but the rooms are closed when in official use, so call ahead. The easiest way into the castle is through the Cork Hill Gate, just west of City Hall.