the gemara states that the stones of the fallen wall are tamei. I was under the impression that anythong mechubar l'karka cannot be an avodah zorah because of the passuk AL heharim (On th emountains, but not the mountains themselves). Shabbat Shalom
Yussie Brick, Brooklyn, New York
If you examine the Mishna in Avoda Zara (45a) which is the source of that statement, you will see that the Mishna asks a similar question. If everything connected to the ground cannot be an Avodah Zara because of "Al he'Harim," why is an Asheirah tree called Avoda Zara? The Mishna answers that because a person was involved in its planting (the exact definition is clarified in the Gemara there on 45b), it is not excluded from the Pasuk of "Al he'Harim."
Even without this Pasuk, the case of the house would also become prohibited because we Pasken "Talush uli'Basof Chibro" -- "(something) disattached that becomes attached" -- stringently regarding Avoda Zara (see Avoda Zara 47b. and PERISHAH Y.D. 6:1 for more on that subject).