We've passed perhaps 30 or 40 of them over the past hour, at the start of our long drive from Delhi toward Agra and the Taj Mahal.
I finally point to yet another structure and ask my guide, "What do you call those?"
"Souna," he says and shrugs in an amused way at what is for him a commonplace sight. But I've never seen a dung structure before - let alone one so elaborately decorated.
Given the overwhelming number of cows roaming with impunity in India - they are everywhere, lying down in the middle of major highways for a nap, wandering through market areas - it's not surprising that a minor industry has evolved around the collection and storage of their dung.
My curiosity is piqued when, as we drive along the crowded ribbon of highway, I notice a woman gathering cow pies in a large basket. In another spot a woman flattens and lays out the circular dung cakes to bake in the hot sun. A little further along, a woman carefully adds some dried dung patties to a half-built structure.
At first I think these brown 6-by-6-foot, 8-foot-high shacks might be inhabited, either by people or animals. But as we pass more of them, I realize that the dung huts are used solely to store dung.
"Why?" I ask my guide.
Trying not to show his surprise at my ignorance, he responds, "For cooking."
These dung huts, I'm told, are storage depots for the fuel.
"But why are they decorated?" I ask. Every single dung hut has myriad geometric patterns carved into it, from wavy lines to elaborate designs.
He looks back at me as if I'm asking, "Why does Martha Stewart decorate her home?"
"Because why not?" my guide replies as we pass a woman painstakingly sculpting her unique pattern into a hut.
After a brief pause, I continue my questioning. "If the cows are free to wander as they please, who owns their dung?"
His response is simple: "Whoever collects the dung owns it."
Finally, I can't resist. "Could you pull over?" I ask the guide as I spy several dung huts ahead. "I want to take a look."
I can almost read his thoughts. Here we are, en route to see one of the splendours of the world, one of the greatest architectural triumphs, and the guy in the back of his car wants a closer look at a dung hut.
After I walk around and photograph the structures, we continue on our journey.
As the noonday sun beats down, we pull off the highway in search of a place to eat. In the open restaurant, my guide excitedly points to a stove: "There," he says. "The dung heats stoves and ovens like that."
I imagine burning dung will produce a rank odour, but it doesn't: it fuels a relatively low-temperature cooking fire.
The cook picks up a couple of pieces of dried dung and flings them into the belly of the stove.
"What would you like to eat?" asks a slim waiter with a razor-thin moustache.
After glancing around to determine what the locals feel safe eating, I settle on the curried chicken, which is both delicious and without after-effects.
We set off on the road, passing several more dung huts. My guide looks at me nervously. "Any more stops?" he asks.
I shake my head.
He smiles. "Next stop, Taj Mahal."