The Tour Thru Tree (Klamath Tree) is a living redwood tree in Klamath, California that was bored through in 1976 & made wide enough for a vehicle to pass.  There are three living redwoods along the California coast that vehicles can drive through (Shrine, Chandelier, & Klamath Tree), & this is the northernmost locale.  There are also known drive-through sequoia trees further south in the state, though one of them toppled recently in a storm.  Been about 18 years since I last visited & nothing has changed, other than the price, to which I ended up driving through this tree five times to get my money's worth.