In spoken English, no one would ever correct you. In written English, in formal writing, some of the stricter English teachers might tell you not to end the sentence with a preposition. In that case, the sentence would be: "What is the most beautiful place on earth to which you have ever been?" Actually, that sounds a bit clumsy ('perfect' English sometimes is clumsy) A better formal sentence would be: "What is the most beautiful place on earth you have ever visited?"

You can also say: "What is the most beautiful place on earth that you have ever been to?"

Is this grammatically correct? [You probably realized that - I'm just being picky]