Speed Of Light Experiment

[T.O.E Dream]

This isn't on why the speed of light is the cosmic speed limit. I want to know how did physicist determine it? What experiment did they perform? What calculations did they make? They obviously didn't go into outer space and shined a light then see how long it took. Did they use a telescope? Help!

[malawi_glenn]

I did some google:
http://www.colorado.edu/physics/2000/waves_particles/lightspeed_evidence.html

One can also measure the speed of light by measuring masses of particles (E = mc^2) etc.