The family are direct descendants of Grace O’Malley (Granuaile) and the house was built on the ruins of her Westport home. Noted German architect Richard Cassels was responsible for constructing the east section of the house in 1730, which was later completed by James Wyatt whose meticulous vision can be seen throughout the house, with ornate ceilings, cornices and fireplaces. The large dining room has all the markings of Wyatt’s good taste. The centre of the house has a grand staircase which extends left and right to the north and south wings, designed by Benjamin Wyatt. A library makes up part of the south wing. Later, in the19th century, a model farm was built with sheds for the animals and storehouses, which later became part of the visitor attractions.
Colonel John Browne (1638–1711) who was married to Maude Bourke, the great granddaughter of Grace O’ Malley, famous pirate queen of Connaught, was first to build a house here upon which the later structure was built. In the grounds, a striking bronze statue of Grace O’ Malley by artist Michael Cooper is a reminder of the distinct origins of the current stately home. While many estates in Ireland are owned and managed by the state, Westport House distinguishes itself not only in that the family lineage is unbroken, but also that the house still contains centuries old English and Irish original silver, paintings and artefacts, many of which are on display.
Among the pictures are portraits by Sir Joshua Reynolds of the 1st Earl of Altamont and William Beechey’s depiction of Hon. Denis Browne. Other works include local landscapes by James Arthur O'Connor and paintings by Chalon, Barrett, Gibson, Opie, Brooks and Lavery. Waxwork figures celebrate the cultural and literary achievements of notables with west of Ireland lineage or connections, such as William Butler Yeats, Lady Gregory and Turlough Carolan. The library boasts old Irish books and the Mayo Legion Flag which remains here since French General Humbert’s 1798 invasion when he joined forces with the Irish rebels and occupied Westport House for a time.
It was John, 3rd Earl of Altamont and grandson of Colonel John Browne, who shifted the village focus from the house to the streets which today make up the town of Westport. The streets, such as Peter Street, James Street, Altamont Street and John's Row are named after members of the Browne family. Much of the town’s early prosperity was thanks to John’s introduction of a productive linen industry. Housing was developed to accommodate the workers and a theatre built at the Octagon to entertain people. The lake at the back of Westport House was also the brainchild of John.
Today, besides the house and grounds the estate has a Pirate Adventure Park with a pirate ship thrill ride, a mini-railway and pedal boats shaped like swans, which offer the chance to get out on the lake under your own steam. A slippery slide, climbing wall and playground keep the little ones busy, while a pitch and putt course, zipwire and zorbing balls are a great way to while away an afternoon. The old farm buildings have been transformed into Gracy's Bar and Cafe, adjacent to a Caravan and Camping Park. Westport House and grounds offer a unique insight into a family home which has been continuously occupied for hundreds of years and whose story is intertwined with the history of the area and its people.