Cuevas de las Manos, Argentina (19/20)

Located in Patagonia, Argentina, the Cuevas de las Manos (Caves of the Hands) is an ancient network of caves adorned with prehistoric handprints. These artworks were created by early human inhabitants over 9,000 years ago, and the caves themselves are located deep within the Patagonian Andes, making them an incredible underground wonder.