You can't help but feel awe-struck by the Romans' bold achievements as you stand before this masterpiece of ancient engineering. Built in the first century, the aqueduct of Segovia – now a ...

Made from more than 20,000 blocks of granite, the aqueduct doesn't use mortar. The Aqueduct of Segovia is in the Castilla and Leon region. Photo: Oscar Del Pozo/AFP via Getty Images.

Still in use to this day, the aqueduct carries water from the Frío River to the city of Segovia. The central section has two layers of arches that stand 28.5 metres (93.5 feet) above the ground.