How do I quote a quote that has quotes in it? [duplicate]

Here's how I'd punctuate the material:

" 'Did you never hear of the "Fountain of Youth"?' "

In diagram form:

(") (')Did you never hear of the (")Fountain of Youth(")?(') (").

The first parens indicates you are beginning to quote a source; then comes a space; the second parens is the comment which was made in the source; the third, the phrase within the quotation; the fourth, the end of that phrase; then comes a space; and the fifth, the end of your quotation from your source.

As @chasly from UK has remarked, the double quotation marks aren't really necessary around the words Fountain of Youth, since by capitalizing Fountain and Youth, you've already identified it as Ponce de León's impossible dream. The double quotations would stay, I guess, if they were included in the text you are quoting from.