Longest Running Experiments

How about this,

Owen Withey, a professor of mechanics at the University of Wisconsin-Madison, who had the foresight to test Concrete mixes and stability and started an experiment back in 1910, and is now known as the 100 year cement experiment, He had made up so many samples that they are thinking of extending it ........

^{or I should say, change the name to say 150 year Cement Experiment.}

Go Badgers

Does this count? (pun not intended)

http://en.wikipedia.org/wiki/Clock_of_the_Long_Now