The Long Now foundation on the longest living institutions. Here's an interesting bit on the bristlecone pine, a tree with an incredibly long lifespan:

The bristlecone exemplifies how an existential crisis gives you practice in terms of how you’re going to survive. The bristlecone is the oldest continuously living single organism that we know of in the world. And the funny thing about the bristlecone is it was not discovered by coring to be the oldest living species in the world; it was postulated because a particular tree scientist had cored other pine species, and as they did that, they found that all the ones in the worst environments were the oldest. And he said: “If you can find the pine species that is living in the absolute worst environment, you will find the oldest species of pine in the world.” And he coined this term: adversity breeds longevity. And so then people went to go find the pines in the worst environment and up at the top of the White Mountains and in the Snake Range in Nevada, and some in Colorado as well, they found three different species of bristlecone, which have been dated to over 5,000 years at this point.