The Bristlecone Pine Forest high up in the White Mountains of California has got to be experienced to be believed. Some trees can live for around 5000 years. And even after they die, the tree trunks can stay for another five thousand years. So it's possible that some of the trunks that one walks amongst are approaching 10,000 years old. These trees are the oldest living things on the planet, and it really blows the mind to think that you are walking in a forest of trees that may have been around when Buddha was walking the earth, some around even before George Burns was born.
You can access this from Highway 395, and then up into the mountains along Route 168 from Big Pine.