BRUSSELS—Albert II, King of the Belgians, abdicated in a televised address to the nation after almost twenty years on the throne, saying he will step down July 21, Belgium's national day.

"It's with emotion that I address every one of you today," he said in the broadcast. "I'm in my 80th year, an age never before reached by my predecessors...my age and health no longer permit me to exercise my functions as I would wish to."

...