Long seen as timid and retiring, he has been thrust in the spotlight since his father's death in April. Last week, as the three-month mourning period for Rainier ended, Albert confirmed news reports that he fathered a child with an African-born Air France flight attendant.

In another surprise, the night before taking the throne Albert told France's TF1 television there may be others with paternity claims, though he didn't offer details.

Little Alexandre — Albert's son with Nicole Coste — will never be eligible for the throne, as Monaco's constitution excludes illegitimate children from the line of succession.

In theory, the constitution could be changed to allow the boy to take the throne. However, both the prince and Coste have said their relationship is over.

Albert won fans for registering himself as the father soon after the baby's birth two years ago and then speaking frankly about what happened.

"He's been very noble about it," said Natalie Coke, a 40-year-old Monaco lawyer. Wearing a shimmery yellow dress and strands of pearls, she scampered up a staircase to snap photos of the prince. "Long live Prince Albert!" she cried.

Hundreds of Monegasques, decked out in finery and elaborate hats, packed the white stone Cathedral of the Immaculate Conception.

Later, in less formal attire, they danced at the city's port to soul and funk music.

Albert automatically took royal powers upon the death of his father but did not formally embrace his role as His Serene Highness until Tuesday. His accession to the throne is a two-step event, with another ceremony expected to draw heads of state on Nov. 19.

The change is enormous for Monegasques, who grew up with Rainier, the "builder prince" who transformed this posh outpost near Nice into a hub of high finance and a playground for the rich. Rainier ruled for 56 years.

The principality has just over 30,000 residents, but 130,000 banking clients worth $78 billion in combined deposits, according to the Monaco Banking Association.

However, it also remains on a blacklist of "uncooperative tax havens" from the Organization for Economic Cooperation and Development — alongside places like Andorra, Liberia and Liechtenstein.

Albert took part in the last five Winter Olympics with his bobsled team and has headed Monaco's Olympic Committee since 1994.

The prince's bachelorhood caused consternation for Rainier, who wanted to ensure the Grimaldi family line. Monaco finally ceded to Albert's single status, revising the constitution in 2002 to allow him to pass powers to his siblings and their children. Caroline has four children; Stephanie has three.

Albert has nonetheless said he plans to marry one day and have a family.