Which of the following is correct?
I am leaving for London.
I am leaving to London.
I have always thought the first one is correct till I came across the name of this painting.
Both are correct, but the first is more common modern parlance. Leaving to is likely an ellipsis of leaving to go to.
"Leave to" is not an American usage - as an American ESL teacher/ editor, I can guarantee that it is not in our grammar books. The accepted standard preposition that completes the infinitive in this case is "for" - in recent times, I've heard an Irish woman using "to" and did a Google search to see if it was perhaps a BE form that I wasn't familiar with.