In Dynasty, it's the mansion seen from the air - the one in which Joan Collins strikes that smirking pose on the grand staircase. The elegant brick and sandstone home also appears in such films as Heaven Can Wait (in which Warren Beatty gets a second life and a great gaff), and The Joy Luck Club. But Filoli, a 43-room, 36,000square-foot Californian mansion, also has close ties to Ireland and direct connections to Muckross House in Killarney. Muckross and the beautiful acreage surrounding it came to the Irish people through the wealthy family which built Filoli. It's a good, old-fashioned Irish-American love story, complete with a supporting cast of indulgent parents and a Californian goldmine.

Filoli - the name is taken from the owner's motto "Fight, love, live", fi-lo-li - nestles at the base of the oak and redwood-forested coastal foothills 30 miles south of San Francisco, and was built at the start of the century by a controversial character named William Bourn.

Bourn was the son of wealthy pioneers, socialite Bostonians who decided to go west at a time when it was still truly wild, when fortunes could be made by risk-takers. His parents settled in the notoriously bohemian town of San Francisco, bought up scattered mining claims, and started working a goldmine known as the Empire. On this mine's massive veins of gold, the Bourn family fortune was built. Eventually, the Empire became the most profitable mine in the state.

Young William Bourn was an astute - some would say, scheming - businessman, a Cambridge graduate who enjoyed the family wealth, building immense houses in San Francisco. He travelled frequently to Europe with his wife Agnes, and often with their only daughter, Maud.

"Well, they were on their way to Europe by liner, and there's this handsome Irish diplomat . . ." - Filoli's caretaker and curator, Tom Rogers, takes up the story. "He was a stunning-looking man. Maud was not a beauty, but boy, did she have money."

By all accounts, though, the attraction was mutual and a whirlwind romance ensued, followed by an enormous Californian wedding in 1910. Then the Irishman, Arthur Vincent, was posted to Zanzibar . . . "Mr Bourn wasn't about to have his daughter living out in Zanzibar," Rogers says.

So Bourn tried to tempt Vincent to stay in Ireland by finding the young couple a suitable house. The house was Muckross and 11,000 acres surrounding the lakes. "You can imagine Vincent," says Rogers, "carefully weighing the amount of money he would have, or having a career." He took the house.

The Bourns travelled frequently to Ireland to visit their beloved daughter and grew to love the Killarney landscape. ("Even if you went by Concorde, I don't know how you'd get around as much as those people did," Rogers says.)

At the time, it was becoming fashionable for wealthy San Franciscans to build large country estates further along the San Francisco peninsula. So in due course the Bourns found a location overlooking a lake (which they already owned) which recalled the view from Muckross, and began to build a house which, even in 1915, cost half a million dollars.

Bourn chose a Georgian revival style - itself evocative of Irish country homes - except that the roof was covered with the local red Spanish tile. And the house, finished in 1917, included exquisite gardens, much like Muckross.

Rogers says that he thinks Filoli is the result of Bourn wanting to feel close to a daughter he missed. "I think . . . he loved her, and he loved the gardens at Muckross. Much of the garden material there was mirrored here."

Towering spikily over the gardens are 210 Irish yew trees, all brought as cuttings from Muckross, then nurtured outdoors at the Empire Mine before being transplanted to Filoli. (The mountain behind Filoli "needs something of the scale and colour of the Irish yew to anchor it," Rogers says.) The Bourns brought clippings of holly and myrtle from Ireland as well. A huge rhododendron and azalea garden which meanders through the forested hillside also evokes Muckross.

They even named features of the land after similar features around Muckross, and a bridge over a creek was named Brickeen Bridge after the bridge between the upper and lower lakes in Killarney.

In 1921, Bourn had the first of a number of severe strokes and by 1924, Rogers says, it was clear he wouldn't be making any further trips to Ireland, so "they decided it would be nice to have pictures of Ireland on the walls". The Bournes hired an artist, Ernest Peixotto, who went with his family to live in Muckross and prepare sketches for murals to fill the enormous ballroom at Filoli.

Because he had never seen Filoli, Peixotto prepared a maquette of the ballroom from the architect's plans, which looks like an elaborate dolls house, and painted miniatures of the murals onto the walls. The maquette was passed down through the Peixotto family, who thought it was just a curio, until the current owners went to see Heaven Can Wait and recognised the room; they've donated the maquette to Filoli, where it's on view in the ballrooom.

The house also has other Irish touches, such as portraits of the Bourns done by Irish painter William Orpen.

By this time, Maud was travelling often back and forth between Kerry and California in response to her mother's urgent telegrams about her father's health. Bourn decided to build a Californian home for his daughter in 1924, engaging the first noted black architect in California, George Washington Smith, to design a magnificent Spanish-style house on the coast at Pebble Beach.

In 1929, aged 46, Maud died unexpectedly after making the Atlantic crossing yet again with her two children. Muckross and the surrounding lands were presented to the young Irish government as a memorial to her. She is buried on a hill at Filoli, along with her parents, who died a few years later. The site is marked by a Celtic Cross, a copy of the one in the ruins of Muckross Abbey.

Vincent, who remained in Ireland, was appointed to the Seanad in 1931.

Filoli was purchased by an avid gardener, Lurline Roth, who further expanded the grounds. She donated the house in 1975 to the American National Trust. Rogers says the trust was largely interested in the gardens and for some time, used the house for storing seeds and gardening tools. But the house was eventually restored and opened to the public as well.

Rogers believes that when Californians looked for "culture" in their new world, they bypassed the east coast they had rejected and went "straight to England" for schooling, furniture, and other accoutrements of fine life. But - happily - the Bourns brought a bit of Ireland to the Wild West as well.

Filoli is in Woodside, California. For information on tours, call 00 1 415 364 2880.