2017 was a banner year for luxury real estate. In January, a Bel Air estate became the most expensive estate in the U.S. when it listed for $250 million; in August, it was dethroned by a $350 million estate in the same neighborhood. From New York to Texas, an influx of high-end estates were listed for jaw-dropping sums. It should come as no surprise that these over-the-top abodes boast equally stunning amenities. From a $30 million rare car and motorcycle collection to a backyard water park, here are five one-of-a-kind amenities that caught our eye in 2017.