A cement quarry near Sucre in Bolivia is home the world’s largest site of dinosaur tracks, known by the locals as Cal Orko. More than 68 million years ago, thousands of dinosaurs flocked at Cal Orko (a lakeside in those times) in search of food and water. This explains the over 5,000 dinosaur tracks, laid in around 350 criss-cross trackways, on a crumbling wall. The most amazing thing about Cal Orko is it features footprints from 330 dinosaur species, from the Cretaceous, just before they went extinct. The fascinating 70-degree rockface is a rather new discovery, found by Bolivian workers, in 1994. It stretches 1.5 kilometers in length and it’s 150 meters tall. Compared to other dinosaur track sites, on any other continent, Cal Orko is by far the biggest and most important. Unfortunately, Cal Orko is in constant danger of crumbling and Bolivian authorities spend $30 million every year, to keep it in place.