We have two giant tree houses - just like you would put in your backyard! Both sit on actual trees that have been hollowed out for you to play in! One log is a White Oak, the other is a Eucalyptus. Both are from San Luis Obispo County on the central coast of California. The company that built our tree houses only uses logs that have fallen or have died. Instead of sentencing these logs to a fate in the wood chipper or fireplace, they give them a second life. The exterior and ground contact wood is redwood and cedar. The shingles are recycled cedar shake shingles. and the railings are made from old oak wine barrel staves.