As a somewhat modernized mid-century build, this Mercer Island home has a lot going for it. The place sports 5-beds and 4,620 sq. ft. of open space interior with tons of floor-to-ceiling windows and just so happens to be the "largest privately held property" on Mercer Island. And while we find the house that is situated on 4.25 acres gorgeous, the waterfront access to Lake Washington wonderfully convenient, and the cottage out back adorable, we're mostly wondering what the deal is with the shiny caboose that's sitting on the lot. What we're even more intrigued about is the listing's comments regarding said train end-piece: "Owner to act as steward for property including pioneer cottage & renovated caboose!" It's unclear as to whether the future owner is expected to simply manage the upkeep of the property or serve as some kind of property ambassador/song-and-dance host for (anticipated) guests. Either way, it sounds like future buyers have quite the task ahead of them. In fact, they may even need to get another job to hold this place down, as the asking price is a whopping $4.75 million.