The Paredones ruins, 2km southeast of town via Arica over the river, are not very well preserved (primarily because they were constructed from adobe rather than stone) although around 10% of the site has been reconstructed so it's possible to get an idea of how it once looked. Their position on a slope above the town is commanding, which is probably why the Incas used it as an administrative control center between the mountains and the coast.
Admission also covers entry to the nearby Cantalloc Aqueducts.
