Here They Are, Science's 10 Most Beautiful Experiments...
Most of the experiments ~ which are listed in this month's Physics World ~ took place on tabletops and none required more computational power than that of a slide rule or calculator.
What they have in common is that they epitomize the elusive quality scientists call beauty. This is beauty in the classical sense: the logical simplicity of the apparatus, like the logical simplicity of the analysis, seems as inevitable and pure as the lines of a Greek monument. Confusion and ambiguity are momentarily swept aside, and something new about nature becomes clear.
Eratosthenes' measurement of the Earth's circumference
Galileo's experiment on falling objects
Galileo's experiments with rolling balls down inclined planes
Newton's decomposition of sunlight with a prism
Cavendish's torsion-bar experiment
Young's light-interference experiment
Foucault's pendulum
Millikan's oil-drop experiment
Rutherford's discovery of the nucleus
Young's double-slit experiment applied to the interference of single electrons
I have to admit that I was less than familiar with 2 of these. How about you? You can read up on them in the New York Times article.