Some 38km southwest of Cuernavaca lie the impressive hilltop ruins of Xochicalco (daily 9am–6pm). While not much is known of the history of this site or the people who inhabited it, it is regarded by archeologists as one of the most significant in central Mexico because of the connections it shows to both the ancient culture of Teotihuacán and the later Toltec peoples. Xochicalco flourished from around 700 AD to 900 AD thus overlapping with both Teotihuacán and Tula and also displays clear parallels with Maya and Zapotec sites of the era. The setting, high on a bare mountaintop, is reminiscent of Monte Albán, the great Zapotec site near Oaxaca.

Like Monte Albán and the great Maya sites (but unlike Tula or Teotihuacán), Xochicalco was an exclusively religious and ceremonial centre rather than a true city. The style of many of the carvings, too, recalls Zapotec and Maya art. Their subjects, however, and the architecture of the temples, seem to form a transition between Teotihuacán and Tula. The appearance of Quetzalcoatl as a human is especially noteworthy, as he was to turn up in this form at Tula and almost every subsequent site, rather than simply as the feathered serpent of Teotihuacán. The ball-court is almost identical to earlier Maya examples, and similar to those that later appeared in Tula.

For all these influences, however, or perhaps because there are so many of them, it’s almost impossible to say which culture was dominant: some claim that Xochicalco was a northern outpost of the Maya, others that it was a subject city of Teotihuacán that survived the fall of that empire. Arriving at the site, first stop in at the museum, on a neighbouring hilltop, where you buy your entry ticket, and can take a look at some of the more portable pieces unearthed here. A carved stele that once graced one of the lower courtyards takes pride of place in the first room, and is followed by numerous slabs of carved stone, a delicate alabaster bowl and some fine jade masks. From here it is a ten-minute walk to the ruins.

Much the most important surviving monument here is the Pirámide de Quetzalcoatl, on the highest part of the site. Around its base are carved extremely elaborate plumed serpents, coiling around various seated figures and symbols with astronomical significance all clearly Maya in inspiration. On top, part of the wall of the sanctuary remains standing, though it now surrounds a large hole.

In 1993 the centre of the pyramid was excavated to reveal the remains of an earlier pyramid inside. The other main point of interest is the Solar Observatory, located to the northwest of the main pyramid and down the hill a little, accessed through the northern ball-court. Here you’ll find the entrance to some subterranean passages, a couple of natural caves augmented by steps and tunnels, one of which features a shaft in the roof that is oriented so as to allow the sun to shine directly in. At astronomical midday (midway between sunrise and sunset) for around five weeks either side of the summer solstice May 14/15 to July 28/29 the shaft casts a hexagonal patch of light onto the cave floor. At any time, the custodian should point out the remains of frescoes on the walls.

The quick and comfortable way to the site is by half-hourly first-class bus headed to Miacatlán from Cuernavaca’s Pullman de Morelos terminal, which will take you to the Crucero de Xochicalco, 4km from the site. There is often a taxi waiting here to run you to the site; otherwise you’ll have to walk. There’s also a very slow and circuitous second-class bus that leaves halfhourly from Cuernavaca’s market bus station and takes you right to the site. If you’re driving, or if you go with a tour, you can continue another thirty-odd kilometres down the road beyond Xochicalco to the caves of Cacahuamilpa, from where Taxco is only a short distance.