Sequoiadendron Giganteum or Giant Sequoia are absolutely indescribable. They are similar to the giant redwoods at Muir Woods.
These are located in the Mariposa Grove at Yosemite National Park in California. The pictures do not do these giants justice as to how large they actually are. Being in the grove is stunning and just beautiful and very surreal.
We paid $25 each for an hour and a half guided tour on a tram which was well worth the money. You can hike through the grove but it is several thousand feet in elevation change.