Home to the Brabazon Family (the Earls of Meath) since 1618 Killruddery House is the most successful Elizabethan-Revival mansion in Ireland and also one of the earliest. In the 1820s the 10th Earl engaged the fashionable architects of the day - Richard Morrison and his son William - to remodel Killruddery. In the 1950s the house was greatly reduced to its present day proportions, but much of the Morrison's design and architecture still remain.

The approach to the house leads through a French Style 18th Century wrought iron gate into a granite forecourt. The forecourt was designed by Daniel Robertson, the architect principally responsible for the layout of the gardens at Powerscourt.

In the entance hall will be seen the stone Coat-of-Arms of Sir Edward Brabazon, Knight, dated 1586. Sir Edward was a Privy Councillor to Queen Elizabeth I and MP for Wicklow. In 1616 he was created Baron of Ardee. The stone Coat-of-Arms was found in 1892 when foundations were being excavated in Cork Street near Thomas Court in Dublin where he lived.

The stairs wind upwards to a small domed lobby. The wrought iron work is by Smith & Pearson of Dublin and the mahogany stair rails were made and put in place by Thomas Donegan. The hanging gilt lantern came from Adare Manor, home of the wife of the 13th Earl.

The domed ceiling above the staircase, hall and gallery was designed by Jones and executed by a local man called Henry Popje (1830).

The Pendulum Clock was made by the 13th Earl. The face is part of a dumb waiter, the pendulum is a copper bed warmer and the weight on the bicycle chain is the lid of a cooking pot. The pendulum is a free movement.

To the east of the hall lies the Library which is incorporated in the oldest part of the House. The central part of the ceiling is a copy of a Charles II design and the chimneypiece and overmantel combine bold Gibbonesque carving of the period with later elements. The bookcases are Chippendale.

The neo-classical style of the Great Drawing Room was probably suggested by the chimney piece which was ordered in Italy from Giacinto Micali in 1817.  The very fine architectural decoration in the ceiling was completed 1824, the date 24th April of that year and the name of Simon Gilligan inscribed on top of the cornice, was first noticed by Elizabeth, Countess of Meath, in 1968 when she undertook the mammoth task of painting the ceiling virtually single-handed.

The next room was known as the ladies small Drawing Room but with the reduction of the size of the house in the 1950s this became the Dining Room. It's magnificent plaster ceiling was executed by Henry Popje, a local craftsman, likewise the Drawing Room and Hall ceilings.