There are a lot of architectural marvels in India from Sun temple to Ajanta and Ellora caves and Kailasa Temple. I personally never understood why more was not written about them, very few know about them.
Mughals never ruled India for more than 200-300 years, and were challenged by many regional players including Maratha's.
India has far more to offer beyond Taj, and I would say if not more equally interesting architectural marvels like Kailasa temple.