From gravity-defying viaducts to simple-yet-sturdy Roman stone arches, the world’s bridges come in all shapes and sizes and have linked towns and cities through the ages. Some of these manmade wonders have made history for their architectural feats, while others offer an invaluable peek into the lives of our ancestors. Here’s our round-up of the world’s most historic, from the 20th century all the way back to 1300 BC.