Archaeologists believe that Mexico's Calakmul, Tikal in Guatemala, and Caracol in Belize were rival cities of similar might and glory. A great thoroughfare once led from Calakmul to Tikal they say - a route for trade and, later, war. Tourism officials have planned a modern-day version of that highway to facilitate tours that include both sites. In the meantime, it's possible to sign on with package tours, but travel between the two sites is difficult. Even touring Calakmul alone can be a challenge because it's so large, which is why area guides offer the option of viewing the site on horseback. The easiest way to find a guide is to ask around in the little town of Xpujil, just east of the Chicanná ruins, or to contact the caretakers of the ruins in the area. You'll need some Spanish to communicate with many of them, but English-speaking guides can be found on the right day, with a little luck.

Besides the twin pyramids and the city's sheer size, it is the presence of more than 130 stelae - freestanding columns carved with glyphs telling stories of historical and religious figures - that distinguishes Calakmul. Their reference to a ruler known as Jaguar Paw prompted experts to conclude that Calakmul is Site Q, a previously unidentified city infamous in Maya history for its commercial power and urge to conquer.

After hearing horror stories about the one-lane asphalt road to this once-great city, we are pleasantly surprised. There are potholes, including a few that seem capable of swallowing our rented Volkswagen Beetle, but nothing that can't be avoided, provided you're alert and driving at a reasonable speed. The going is slow, but the wildlife on either side provides ample distraction.