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The famed Monte Carlo casino (search) was closed, its spinning roulette wheels at rest as Monaco mourned the death Wednesday of Europe's longest-reigning monarch, Prince Rainier III (search), who worked to overcome this tiny principality's reputation as "a sunny place for shady people."

The throne now goes to Prince Albert II, Rainier's only son with actress Grace Kelly (search).

In power for 56 of his 81 years, Rainier was the only ruler many of Monaco's 32,000 residents had ever known. A veritable father-figure, he dragged Monaco into the modern age while preserving much of its Mediterranean charm and royal trappings.

Before age slowed him, Rainier poured his energies into public works, earning the name "the builder prince." He put Monaco — which is smaller than New York's Central Park — on the world map with his April 18, 1956, marriage to Kelly, who gave up Hollywood fame to become Princess Grace.

Albert, 47, has been groomed from birth to succeed Rainier. Multilingual, U.S. educated, and a five-time bobsledding Olympian, he was at his father's bedside when Rainier died at a hospital overlooking Monaco's yacht-filled main harbor.

Rainier had been treated there for the past month for heart, kidney and breathing problems. Albert took over the royal powers last week because of Rainier's ill health.

Rainier's funeral will be held April 15 at the 19th-century Monaco Cathedral where he and Princess Grace wed. He is expected to be buried alongside her.

At the traditional midday changing of the palace guards ceremony Wednesday, drums were covered with black cloth. The body of Rainier, whose family dynasty took power in 1297, was moved to his hilltop palace where it will in lie in state, the palace said.

The Monte Carlo casino closed in a sign of respect. Monaco's soccer team postponed a weekend match.

Flags, already lowered for Pope John Paul II, remained at half-staff. Monaco's TV networks interrupted programming with documentaries on Rainier's life and reactions to his death.

"Each of us feels like an orphan because the principality has been marked by his imprint over the 56 years" of his reign, said Patrick Leclercq, head of Monaco's government.

Rainier's doctors called Albert about 30 minutes beforehand to tell him the end was near, the palace said. The palace did not say if Rainier's daughters, Princesses Caroline and Stephanie, were with him when he died.

Christopher Le Vine, whose mother is Princess Grace's last surviving sibling, said Albert and Caroline called to inform him of Rainier's death.

"They're doing remarkably well under the circumstances," he said.

He said he and other Philadelphia-area relatives will go to Monaco for Rainier's funeral. He said the prince had a "unique sense of humor" but he expects Albert to make his own imprint on the French-speaking principality.

"It's not something that he hasn't anticipated over these many years. He will make his own space there," Le Vine said.

Albert is unmarried and has no children — a source of consternation to Rainier, who worried about continuing the Grimaldi family line.

Monaco changed its succession law in 2002 to allow power to pass from a reigning prince who has no descendants to his siblings. Albert's sisters have children.

From the palace's crenelated sandy-colored walls, perched high on a cliff that dominates Monaco, Rainier could survey the domain he turned from a Riviera backwater into a playground for the rich. Its winding streets are turned into a racetrack every spring for the Monte Carlo Grand Prix.

During Rainier's reign, Monaco expanded its territory by 20 percent with land reclaimed from the sea — allowing the government to boast that Monaco was the only country to grow so much by peaceful means.

He oversaw construction of a new port, an artificial beach, a cultural center and an underground railway station. A breakwater project to allow large yachts and cruise liners to dock in the main harbor cost $420 million.

Monaco also worked to overcome a reputation as a haven for questionable financial transactions, drug barons, money-launderers and tax dodgers.

In 1993, Monaco gained the political recognition Rainier sought with its entry into the United Nations.

Last year, having enacted reforms ranging from electoral rights to money laundering, Monaco joined the Council of Europe, the continent's foremost human rights organization.

Soon after the Sept. 11 attacks, Monaco began investigating its banks and financial institutions for terror-related funds. It also signed the U.N.'s International Agreement for the Repression of Terrorist Funds, pledging to detect and freeze ill-intended assets.

When Rainier assumed the throne on May 9, 1949, Monaco's economy was driven by its roulette tables: Gambling proceeds represented 45 percent of government revenue. Now, casinos contribute less than 4 percent and Monaco relies on industries like pharmaceuticals, plastics, banking and tourism.

"I am like the head of a company," Rainier once said.

In an outpouring of condolences, world leaders credited Rainier with courage and praised his leadership.

President Bush said in a statement that Rainier "will be remembered as a respected leader who secured the prosperity of Monaco's people."

"Monaco and the United States have long had a special bond of friendship," Bush said.

Britain's Queen Elizabeth II sent a message of condolence. Rainier's death means the queen, who acceded to the throne in 1952, becomes the longest-serving monarch in Europe.

But some residents worried whether Rainier's passing also meant the end of Monaco's golden days.

"It was a life, a way of living, of managing the principality," said Odette Sainsaulieu, a 66-year-old Monegasque who went to the hospital hoping "to say a final goodbye."

Rainier Grimaldi was the 30th descendant of Otto Canella, who founded the house of Grimaldi. Born May 31, 1923, the son of a princess born out of wedlock, Rainier was heir to a family with a stormy past — a harbinger of scandals to come.

The marriage of his great-grandfather Prince Albert to Lady Mary Douglas Hamilton was dissolved in 1880. Albert's son, Prince Louis II, had a youthful romance with a French girl in Algeria that produced Princess Charlotte, Rainier's mother.

In 1920, Charlotte married Rainier's father, Prince Pierre de Polignac. Rainier was born three years later, shortly before his parents divorced.

Educated in England, Switzerland and France, Rainier undertook military service near the end of World War II. He became Monaco's ruler at age 26 when his grandfather died.

As a youth, Rainier had a long romance with French actress Gisele Pascal, became a fan of jazz and studied oceanography, later helping to finance Jacques Cousteau's Oceanographic Institute in Monaco. He also developed a love of fast cars.

Rainier, who reportedly once considered Marilyn Monroe for his bride, met Kelly in 1955 when he was 31 and she was the 25-year-old star attraction of the Cannes Film Festival. She already had an Oscar from the 1954 film "The Country Girl," one of only 11 movies she made.

In January 1956, they announced their engagement and were married in April. Ten months later they had the first of their three children, Caroline. Albert's birth came the following year, on March 14. Stephanie was born Feb. 1, 1965.

Rainier never remarried after Grace's death in a car accident on Sept. 14, 1982 — and often cut a lonely figure in his latter years.

"She was always present and ready to do things either with me or for me if I couldn't do them," Rainier said in a 1983 interview. "Let's say the change is that we worked as a team and the team has been split up."

In the years following Princess Grace's death, the family increasingly became grist for the world's tabloids.

Caroline's rocky first marriage ended in 1980, and her second husband was killed in a boating accident in 1990. Her third husband, German prince Ernst August of Hanover, was ordered to pay more than $440,000 in 2001 for yelling at an editor of a newspaper that reported he had urinated in public.

Stephanie had two children by a former bodyguard, then married him in 1995. The marriage lasted 18 months, ending after he was photographed cavorting poolside with a Belgian stripper. She had a third child in 1998 and refused to reveal the name of the father. She married a Portuguese circus acrobat in 2003; the palace has declined to say if they are still together.