As you wind through the main gate to the Agra Fort, you soon find yourself going up a long walled incline. As a visitor, I thought this added to the suspense of entering such a legendary fort. But for Akbar and the Mughal kings who built it, their design was meant to be much more than just awe-inspiring. The Mughals concluded that if an invader were able to penetrate the main gate, they should have as difficult a time getting into the palace inside. So imagine hundreds of heavily armoured infantryman charging up a steep incline as angry Mughal warriors poured boiling oil from above the walls. Even for those poor souls who survived the burns, it'd be next to impossible to continue uphill on the slick, burning surface.