Michael Keane stopped the coach he was driving just shy of the border crossing into Northern Ireland and turned to face his passengers. The songs and jokes with which he had been entertaining them had gone silent, and his playful demeanor was now sober.

"You're most welcome here, and you're safe," he told them. "But the old animosities remain. Don't ask people whether they're Catholic or Protestant, and don't make jokes about religion with anyone you meet, especially in pubs."

Someone on a previous trip had done exactly that, and the consequence had been a sound drubbing.

With that bit of business out of the way, the rest of the drive through Northern Ireland was like prying open the lid of a long-hidden treasure chest. For years it was off-limits to visitors because of the religious and political "Troubles." Now, thanks to the 1998 Good Friday Agreement that former President Bill Clinton helped to broker, the natural beauty, history and culture that remained hidden for decades are once again accessible.

A good place to begin exploring for anyone driving up from Dublin is Down Cathedral in Downpatrick. This is the traditional burial place of Ireland's patron saint, St. Patrick, who taught the principles of Christianity without identifying with any particular church.

"This is the most important ecclesiastical site in all of Ireland," said cathedral guide Joy Wilkinson. "We want people who come here to feel it belongs to them. We are all one under God."

Wilkinson explained that early Celts first worshipped here, and the place has been a Benedictine monastery and an Anglican church where John Wesley, father of the Methodist Church, occasionally came to preach. She also dispelled the myth of St. Patrick driving snakes out of the country since there were never any there to begin with.

"They were a symbol for evil," she said, comparing the analogy to the biblical serpent that tempts Eve in the Garden of Eden.

A short drive northeast and a ferry ride across Strangford Lough lead to another tranquil spot, Mount Stewart. The stately home was begun in 1804 by Robert Stewart as a showplace of architecture and style and improved upon by subsequent generations.

When Charles, the sixth Marquess of Londonderry, brought his bride, Edith, to the property in the early 20th century, she pronounced it "the dampest, darkest and saddest place I had ever stayed." She installed electric lights and central heating and simplified the Edwardian fussiness that had previously characterized the decor.

Her greatest contribution, however, was the gardens that surround the mansion. Owing in part to a mild climate because of the nearby sea and to the help of unemployed soldiers after World War I, she was able to experiment with plants and create colorful formal gardens that require a good afternoon to see.

Due west, Belfast, Northern Ireland's capital, provides a jarring change of pace. Here loyalist murals painted on the sides of buildings recall previous hostilities, and plaques on homes commemorate casualties in the sectarian war. A "peace fence" still separates Catholic and Protestant neighborhoods. Keane shook his head as he drove through.

"These were working-class people killing working-class people, for God's sake," he said.

Times are better now, however. Guide Ken McElroy, who was awarded the prestigious MBE by Queen Elizabeth II for his work in bringing tourism back to the area, said airlines from the rest of Great Britain now offer cheap weekend flights, some 45 cruise ships call at the port and there has been a huge resurgence in the building of hotels. To prove what he'd said, he pointed to a parade of cranes that dotted the horizon.

And there's a lot to see — such as the remains of "Linenopolis," Belfast's linen operation, and the Harland and Wolff shipyard where the Titanic was built. The Ulster Museum inside the 19th century Botanic Garden reveals more of the country's history. For shoppers there are Victoria Square and Castle Court Center, and after dark the nightlife is hopping. The Crown Liquor Saloon opposite the Hotel Europa (the most frequently bombed hotel in the world, according to the Guinness Book of World Records) has recently been restored to its Victorian splendor with private booths called "snugs" that were once used by prostitutes.

The narrow coastal road heading north out of the city passes by dazzling green hillsides where sheep graze along precarious pathways and on to medieval Dunluce Castle, part of which has tumbled into the sea. At the northernmost point is the Giant's Causeway, a natural wonder consisting of some 38,000 hexagonal columns created by volcanic activity 60 million years ago. Irish legend has it, however, that the rocks were laid down by giant Finn MacCool as a way to reach his Scottish rival, Benandonner, across the North Channel. This is Northern Ireland's only World Heritage Site, and visitors are encouraged to walk and climb on it freely.

South and west of the causeway is Derry (the Catholic name) or Londonderry (Protestant), the walled city that is one of the oldest inhabited places in Ireland. Here, too, are murals and a peace fence recalling the fighting that ended just over a decade ago.

"This is a peace process, and it will take generations for us to heal," said local guide Ronan Macnamara, whose Chinese-Irish heritage has resulted in a Buddhist perspective on the state of his country's affairs. "Most people are just trying to get on with their lives."

He said a peace bridge across the River Foyle is expected to be finished by May, and he pointed out a large sculpture titled "Hands Across the Divide" by Maurice Harron at the west end of Craigavon Bridge that depicts two figures with their hands almost — but not quite — touching. He added that behind the religious discord were economic problems that are now being solved, in part, by renewed tourism.

Due south in Omagh is the Ulster American Folk Park, a truly interactive museum that brings the Irish emigration experience to life. On one side of the park are cottages, churches, forges and stores that would have been used by Irish people before they left for the United States. Many are the actual buildings that have been rebuilt on this property. One of the most significant is banker Thomas Mellon's Irish homestead, which stands on its original site. After a tour of a reconstructed ship that has been outfitted as it would have been for the emigrants' long voyage across the Atlantic, visitors emerge into the New World on a Pennsylvania street.

Docents in period costumes are on hand to teach guests about the emigration experience. On St. Patrick's Day they'll hold an "American Wake" — a re-enactment of the celebration a family would have held, singing and dancing before one of their loved ones left, probably never to be seen again.

A good last stop before crossing the border back into the Republic of Ireland is Belleek. The high-quality pottery made here is as much an Irish tradition as Wedgwood is in England. It's possible to ship pieces home or to pick up small, elegant gifts to carry on the plane.

WHEN YOU GO

Getting there: Joining a tour is a good way to learn Northern Ireland's complex history as you see the sights. My CIE Tours International guide was also a part-time college lecturer in Irish history: www.cietours.com.

Money: The Republic of Ireland is part of the European Union and uses the euro as its currency, but Northern Island is loyal to the English crown. Be sure to bring pounds sterling.

For more information:

Down Cathedral: www.downcathedral.org

Mount Stewart: www.nationaltrust.org.uk/mountstewart

Belfast information: www.gotobelfast.com

Giant's Causeway: www.nationaltrust.org.uk/giantscauseway

Derry/Londonderry: www.derryvisitor.com

Ulster American Folk Park: www.folkpark.com

Belleek Pottery: www.belleek.ie