9 Greatest Feats of Human Engineering

Hagia Sophia
Is a former orthodox patriarchal basilica which was later converted to a mosque and which is now a museum. It is located in Istanbul, Turkey. It was built with Ashlar brick and is 82 meters in length. It is believed that this monument had its construction beginning in 532 and the same was completed in 537 which was approximately 1474 years ago.

Florence Cathedral
This main church in Italy is popularly known as the Basilica of Saint Mary of the Flower. The architects behind this massive monument are Arnolfo di Cambio, Filippo Brunelleschi. The construction began in 1296 in Gothic style and was completed structurally in 1436. The exterior of this monument is designed brilliantly with polychrome marble panels in various shades of green and pink bordered by white and has a resemblance of the 19^th century Gothic Revival. The dome was once considered to be the largest in the world and it is one of the biggest churches in Italy.