Leonardo da Vinci designed this bridge for the Ottoman Empire

Plans for a bridge designed by Leonardo da Vinci have recently been discovered.

The 16th century bridge would have been the longest in the world at the time but the design was never used. 

Da Vinci sent the design in response to Sultan Bayezid II’s request for submissions for a bridge to connect the area that is now Istanbul to neighbouring Galata.

It was about 10 times longer than typical bridges of that time.

A group of researchers from MIT have built a replica of the bridge to test how sturdy it would be. The team used 3D printing to create 126 blocks to emulate the thousands of stone blocks that would have been used to make the actual bridge. The model was 500x smaller than da Vinci’s bridge would have been. The group then presented the results at the International Association for Shell and Spatial Structures conference in Barcelona.

"It's incredibly ambitious," said Karly Bast, who worked on the project. "It was about 10 times longer than typical bridges of that time."

Back in 1505, when da Vinci submitted the design, most bridge supports were a semi-circular arch and would have required at least 10 piers to support it. Da Vinci’s design, however, was a single arch, flattened at the top, which would have been tall enough to let boats pass underneath.

"Was this sketch just freehanded, something he did in 50 seconds, or is it something he really sat down and thought deeply about? It's difficult to know," Bast said.

“But this testing of da Vinci's design suggests that he spent some time carefully thinking about it.

"When I put the keystone in, I thought, 'This is going to work.' That was the critical moment when we first put the bridge together. I had a lot of doubts.  And after that, we took the scaffolding out, and it stood up. It's the power of geometry. This is a strong concept. It was well thought out."

(image: livescience.com)