Privately owned missile silos:

There's a hot market for demilitarized ICBM silos. There are three of them on offer at eBay right now, with the asking price of $500,000 per silo, which includes underground and above ground support facilities. Hundreds of ICBM silos have been sold off in the last twenty years, as new missile forces were reduced with the end of the Cold War, and the enactment of arms reduction treaties. Most of these are located in remote areas. For example, the three silo complex being offered on eBay sits on 57 acres in central Washington State.

This one is kind of prime because, unlike most of the others, it is dry. Your typical missile silo complex sits under the water table, and needs pumps to keep the water out. When these silo complexes are demilitarized, most electrical and mechanical gear (including a lot of the plumbing) is removed. The water, and some wildlife, return.