One of the most ambitious, controversial, and just plain bizarre schemes to hatch at the millennial end of the 20th century was Biosphere 2, which stands in the Arizona desert at the northern foot of snowcapped Mt. Lemmon. Developed in the 1990s by a New Age group called Synergia Ranch and funded (to the tune of $200 million) by Texas billionaire Ed Bass, Biosphere 2 was originally intended to simulate the earth’s entire ecosystem in order to test the possibility of building self-sustaining colonies on other planets. A crew of four “biospherians” spent two not entirely self-sustained years sealed inside, but amid allegations of corruption and deceit, the project imploded. The University of Arizona eventually took over running the domes, and has since redirected the focus onto research into the effects of greenhouse gases and other ecosystem changes. The surrounding land has been sold and is slated to become yet another upscale housing development, but Biosphere 2 itself should stay open for self-guided tours (520/838-6200, daily, $20, kids under 5 free). To reach Biosphere 2, follow Hwy-79 to Oracle Junction, 25 miles north of Tucson, then turn east onto Hwy-77 for 6 miles and follow the signs.