The weird beauty of Tulum cannot be fully domesticated by the routines of tourism. That said, the place is visited by two million people a year, leading to wear and tear, and if the Riviera Maya grows as expected, that number will also grow. By the year 2030, a local development authority speculates, there will be an additional ten thousand hotel rooms in the town of Tulum, which lies a couple of miles south of the ruins, and three thousand more within the national park that surrounds the ruins themselves. At a hearing on the matter, a representative of Mexico's National Institute of Anthropology and History pointed out that the walled remnants of this city represent the best surviving example of the Maya's late (a.d. 1200–1520) East Coast architectural style, and that directly beneath the areas marked for new construction, four of the longest underground rivers in the world meet.

In the newspaper summary that I read, the representative did not delve into the additional impact of housing the people required to service the new hotel rooms, but the responsible handling of bedroom communities has been identified by environmentalists as a key issue. Within days of the hearing, opposition had caused the development authority to backtrack, but the conflict appears headed for the courts.

I don't know that I've ever been in a place where roads seem so like clues to be read—clues to both the possible future and the hard-to-picture past. At the city of Cobá, built several centuries earlier than the Toltec-influenced trade center of Tulum, you can see an eroded but impressive specimen of a sacbé, one of many ancient limestone causeways, some of which are said to have extended more than sixty miles. The old Mayan roads linked what was less a unified empire than a web of individual settlements, some rising in strength as others fell away.

There is one road above all that I'm eager to see, since last year its bumpy carelessness helped define for me a place of off-the-grid beauty. This is the Boca Paila Road, lined with small hotels and cabanas, lying two and a half miles east of the town of Tulum and leading down into the biosphere. I'm particularly interested in the lower portion of the road, with sheltering mangrove on one side and beach on the other. When I was last there, its surface of densely packed orange sand was pitted like the face of a teenager. Palm trees rudely leaned into its path, and to drive certain portions after a rainfall was like riding a bucking bronco. Yet it all worked, somehow, with the surrounding vibe of purposeful slowness.

The small establishments along the Boca Paila Road might seem to lack conventional amenities. Merely to make reservations can require slow-paced e-mail negotiations with owners and inconvenient methods of prepayment. Several of the more sophisticated operations also tend to be eco-inclined, dimming the lights at night and relying on fans, mosquito nets, and windows designed to draw a night breeze rather than air-conditioning. But in exchange for these mild constraints you can enjoy an intense, quiet privacy, which in its own way is the height of luxury.