Which one is grammatical?

There is no need for the preposition at.

Where is your house located?

"at" is not necessary because it cannot be used with "where".

Where do you live? NOT "Where do you live at?"

Anonymous1.Where is your house located?

Even this is unnecessary. It would be better to simplify it as: Where is your house?

But does using it make the sentence ungrammatical though? I think I've seen some instances in which "where" is used with a preposition though I cannot think of any at the moment

I am pretty confused about grammatical use of prepositions when it is used with words like "where" or "what" and the like, for example when you say "Where do you come from?" it is grammatical because the word 'come' in this sense is used with the preposition 'from', like in "I came from Canada" or something. In my case, when you change that sentence it could become "my house is located at (somewhe

AnonymousI think I've seen some instances in which "where" is used with a preposition though I cannot think of any at the moment

You may sometimes hear "Where're you at?" (mostly in American movies)

While ungrammatical, the justification for at can possibly be attributed to the sentence sounding strange without the preposition (note that where'

IvanhrYou may sometimes hear "Where're you at?" (mostly in American movies)

That's something that speakers of American English often say. The "at" is superfluous so, it would be correct and simpler just to say "Where are you?"