Occupying a remote corner of Guatemala near a border shared with Mexico and Belize , the Middle Preclassic site of Río Azul was rediscovered in 1962. The population reached its zenith sometime between A.D. 410 and 530, coinciding with the installation of the new Teotihuacán rulership at Tikal , with which it also shares a similar city layout. The population is believed to have reached 5,000 inhabitants occupying an area of about 300 hectares (750 acres).
Río Azul played an important part in the expansion of Tikal’s dominance of the Petén area, likely as a vital trading post linking Tikal to sites on the Caribbean coast and farther north to Central Mexico. It also served as an important ally against Tikal’s archrival, Calakmul . By A.D. 530, however, the tables had turned and Calakmul invaded Río Azul, forcibly allying it.
After Tikal regained its former splendor in the Late Classic period, Río Azul’s population once again soared and new monuments were built, further reflecting the city’s status as a subservient outpost to the area’s more powerful cities. It rounded out the Classic period invaded by Puuc Mayans from the Yucatán in A.D. 830.
Río Azul’s claim to fame is the discovery of several tombs with bright red paintings on white plaster. Many of the burial scenes contain elements of Teotihuacán culture, providing further evidence of strong influence on Tikal and its satellite cities.
Unfortunately, Río Azul fell prey to some of the most severe looting ever seen in the Mayan world in the 1960s and ’70s. A minor section of these murals lining royal burial tombs remains intact, as most were chiseled out and taken away.
There are some more recent discoveries, though not nearly as elaborate, pertaining to burial chambers of noblemen. It is hoped Petén’s newer discoveries can avoid the same fate through better protection.
Many of Río Azul’s treasures are in private collections, though you can see several pieces on display in Guatemala City’s Museo Nacional de Arqueología y Etnología .
Río Azul is connected by road to Uaxactún  at a distance of about 95 kilometers. The road is passable only in the dry season via 4WD. About halfway, you’ll pass the Río Azul . It is also possible to hike or ride horseback to this remote outpost, taking about five days each way. Trips can be arranged at Campamento El Chiclero in Uaxactún.
Once at the site, you’ll need to cross the Río Ixcán to the guards’ campsite on the other side, where you can stay the night. The archaeological site proper is another six kilometers away, along a good road.
The road continues north another 12 kilometers to the intersection of the Belize, Guatemala, and Mexico borders, a place known as Tres Banderas. There are plans to improve the road from Uaxactún clear to the border at Tres Banderas under the auspices of a regional initiative known as Plan Puebla Panamá. So far, conservationists have been able to get the project shelved, arguing that the new road would bring in settlers, much as in Laguna del Tigre National Park  to the west, with devastating consequences for this well-preserved swath of forest.