Our ancient roots dating back to hundreds of centuries is not something we ponder over too frequently. But if at all we do, the sheer richness and diversity of our history is bound to leave us spellbound. With primitive tools and calculation methods in a time when modern day building materials and technology were unimaginable, our forefathers built temples and cities that have survived till date. Such ancient structures, which once formed the nervecentre of trade, education, religion or culture, bowl us over with their engineering ingenuity, sculpture and designs even in this modern era of science and technology. We list some such oldest architectural marvels we can proudly look back to and call our own in this I-day special.