Freo Big Fella said:
There's a great story about Telsa going to a bridge in Omsk Russia, running electricity through certain points and applying pressure on others, and damn near bringing it down. Absolute Genius.
Tesla was also apparantly the master of the thought experiment - that is, he could construct a mental model of an experiment so accurately that he could run the experiment mentally, and his results were repeatable the vast majority of the time - this is one of the reasons his work is largely not understood - he didnt really feel any need to notate as thouroughly as others might, becasue he'd already thought it through, and knew what the answer was.
He was also very, very scared of spheres. My favourite mad scientist ever.
On the OP - yeah, Da Vinci was IMHO the top dog. The scope and depth of his brilliance has never been seen since.