True Polar Wander (TPW) can be a major driver of tectonics and climate change on one-plate planets, such as post-Noachian Mars. But did TPW actually occur? I will summarize work at Berkeley testing this hypothesis, and its place in understanding the last three billion years of climate change on Mars. I will also present results from an ongoing Berkeley/Ames collaboration using General Climate Models to further test late-stage polar wander. This talk may not turn your view of Mars upside down, but it could rotate it by about 8 degrees.