Alto de las Piedras is one of the outlying archaeological sites that make the San Agustin region feel much larger than the main park. Set near Isnos, it preserves carved stone figures, tomb platforms, and ceremonial spaces from the same broad culture that produced the better-known statues around San Agustin. The setting is rural and open, with the monuments scattered enough that you feel the landscape as part of the site.
The famous figure here is often called the "Double Self", a compact but unsettling carving that rewards a closer look. Most travellers visit Alto de las Piedras on a full-day jeep circuit with Alto de los Idolos and the nearby waterfalls. It is too far to treat as a casual walk from town, but it belongs on the short list if you came to San Agustin for archaeology.