@rockstar08 is a poet not me. But that was a good attempt.
On topic:
Yes, I believe that TajMahal was built on a temple. It is very well documented that under muslim rulers, many hindu temples were destroyed and later renovated. It began with the first idol breaker Mahmud of Ghazni and his example was followed by Mongols, Turks and Persians. And in many cases the temple materials were re-used. For example Bellary, Masjid built by Tipu Sultan (1789-90), Eluru Fort where temple materials were re-used etc.
The strongest evidence regarding Taj Mahal is the foundation on which it is built. It is exactly like Angor-wat (Cambodia), which is one of the greatest hindu temple ever built. Taj mahal was not designed by a single person (as popularly believed).
If you pick up any newspaper today, you will find pictures of how ISIS is destroying old relics and statues. Say a 500yrs later, ppl would find it hard to believe that once upon a time Buddhists lived in Afghan and Iraq.
Now dont misunderstand me, I am a proud Indian, and Taj Mahal is one of the most stunning symbols of India's rich history. The credit goes to Shah-jahan for commissioning something so spectacular and going to great lengths to see it completed. So even though Taj was built on a temple, i dont have any issues with it, its not as if Tejo mahalaya needs to be rebuilt.