This is the label for the whole collection, and it deserves a longer look: the Precolumbian Chiefdom Settlements with Stone Spheres of the Diquís. UNESCO placed four sites on its World Heritage list in 2014, all within the lower delta of the Térraba river in southern Costa Rica, a few kilometres from Ciudad Cortés. They are the best preserved remains of a culture that thrived here for centuries before European contact, and the reason the word chiefdom appears in the title is that archaeologists see here a society of ranked leaders, craftsmen and farmers, ruled from house-mounds.
The people of the Diquís were skilled potters and goldworkers, and the spheres are their best-known monument. The finest are made of a hard, dark stone, ground and polished until they are almost perfectly round, and they range from fist-sized to well over two metres across. Many were found when the United Fruit Company cleared the land for banana plantations in the 1930s, and some were dragged away and displayed in gardens in San José and around the country, where you can still see them. Their original meaning is lost, but their presence is hard to ignore.
The setting is lowland tropics, wet and flat, ringed by mountains that you can see on a clear morning. The roads are straightforward, the traffic mostly local, and the delta is crossed by wide rivers with muddy brown water that carry the memory of all the rain on the Talamanca range. Heat builds fast after nine, and afternoon downpours are common, so shift your riding to the cool hours and keep your phone dry.
For fuel, rely on Buenos Aires, about thirty kilometres away and the nearest larger town, rather than counting on Ciudad Cortés. Sphere sites can have limited opening hours and entrance fees, and the exact arrangements are best confirmed locally. If you only have time for one site, choose the one with the on-site museum and give the rest a glance from the road, then spend the heat of the day under a tree with a cold drink and a good look at the riverbank.