It's in Calakmul itself that we come closest to nature. We follow a well-marked trail through the jungle, where ancient trees shelter us from the sun and the birds call out our progress. And then the path opens up into a clearing, and beyond the jungle's edge is the great pyramid, spotlit by the sun. As we make our way toward it, we hear a rustling in the trees overhead. A group of howler monkeys follows along, jumping from treetop to treetop.

When we reach the top of the pyramid and gaze over the top of the rainforest toward its as-yet-unexcavated twin, we hear a deafening, eerily penetrating roar. It rises and falls like the breeze through the canopy below. Belatedly, the monkeys are declaring their territory.

On our way back through park headquarters, we discover why: We're the first to sign the Calakmul guest book in three days. The caretaker nods and grins when we point this out. "Sometimes we have a few people in one day, sometimes none for days at a time," he says. Presumably, the news that one can climb a pyramid taller than Chichén Itzá's hasn't yet reached the rest of the world. Or the news about Jaguar Paw and his ambitions revealed in the stelae. Or the fact that on a clear day from atop Calakmul's pyramid, you can look through binoculars across more than 25 kilometers of jungle and maybe, just maybe, see its rival, Tikal.

Immerse yourself in Mayan culture for long enough, and the past might seem incredibly present. A few days later, when we trek down a jungle trail toward the ruins of Dzibanché, armed with incense against the mosquitoes, I look through the trees past a pyramid and see an expanse of water. I look again, and the pyramid is surrounded by earth and trees, the water nowhere to be seen. Then I hear the bellow of a conch-shell horn from atop a temple.

"Atzín is making an offering to the ancestors," says Malina, one of our guides from Rancho Encantado, the resort we've made our base in the southeast part of the Yucatán peninsula.