Liechtenstein’s Franz Josef II Dead at 83 : Royalty: The tiny nation’s popular prince was the world’s longest-reigning monarch.

Prince Franz Josef II of Liechtenstein, head of state of the tiny principality during a half-century that saw it become one of the world’s richest nations, has died at age 83, the government said today.

He was the world’s longest-reigning monarch when he died late Monday after a long, undisclosed illness and less than a month after his wife, Princess Gina, died at age 67.

Franz Josef was the 12th ruler of the 270-year-old nation, last remnant of the Holy Roman Empire. The principality covers 61 square miles of rolling land and rugged mountains between Switzerland and Austria.

His 51 years as head of state spanned the rise of this tiny democratic state from an underdeveloped and rural country to a sophisticated industrialized nation with one of the world’s highest per-capita incomes.

He enjoyed great popularity among the 28,000 inhabitants, often mixing with them in the streets of Vaduz, the capital.

“I am ruling over a happy country,” the prince once said in a rare interview. “It is a happy country because it is small.”

In 1984 he handed over his executive powers to his son, Prince Hans Adam, the oldest of his five children. But he retained the ceremonial role of head of state and continued to meet many well-wishers every year during the festivities marking his birthday on Aug. 16, a public holiday.

The family’s art collection of 1,400 Rubens, Van Dyck and other old master paintings has a current estimated value of $150 million.

Prince Hans, 44, who now succeeds as monarch, is a trained economist.