"We seem to be determined to vandalize these few remaining sites which retain the kind of human scale and timeless character that so attract people to them and which increase in value as time goes by," Charles said at St. James' Palace.
The speech was a challenge to London Mayor Ken Livingstone's support for a project near the Tower. The building, known as the "Shard of Glass," would be Britain's tallest skyscraper.
Charles suggested tall buildings be clustered in corporate areas. He pointed to Paris' La Defense, a business district full of skyscrapers kept separate from the city's famous museums and landmarks.
"The key point I want to make is that I am not opposed to all tall buildings," he said. "My concern is that they should be considered in their context; in other words, they should be put where they fit properly."
His speech also took aim at plans to build more than 3 million new homes by 2020.
"My concern is that London will become just like everywhere else with the same homogenized buildings that express nothing but outdated unsustainability," he said.
In 1984, Charles criticized a proposed addition to London's National Gallery, calling it a "monstrous carbuncle." More skyscrapers in London would be worse, he said.
"Not just one carbuncle, ladies and gentlemen, on the face of a much-loved old friend, but a positive rash of them that will disfigure precious views and disinherit future generations of Londoners," he said.
