And, when he (his son) was old enough to walk with him, he said: “O my son! I have seen in a dream that I am slaughtering you (offer you in sacrifice to Allah), so look what you think!” He said: “O my father! Do that which you are commanded, Insha’ Allah (if Allah will), you shall find me of As-Sabirin (the patient ones, etc.).”
Then, when they had both submitted themselves (to the Will of Allah), and he had laid him prostrate on his forehead (or on the side of his forehead for slaughtering);
And We called out to him: "O Abraham!
I don’t see any mention of an altar.

But maybe there was one. Who knows?
Anyway, nothing wrong with altars in general. I’m just saying I never heard about Adam and Eve building one. Their sons offered sacrifices though, for sure, possibly on an altar.
There’s no reason to have an altar in a mosque–it doesn’t play an function in the practice of Islam. I’m not sure exactly what you’re getting at though.