Looks like a purple martin house,...I'm sure the former owner would be happy to tell you the history of this house and what was nesting in it.
Not sure if it's easy to take down, most purple houses are taken down in fall, some are on a winch system like mine,..needs to get cleaned out before the new arrivals in spring. Search at what date the arrivals are in your area, sometimes you need to plug up entrance,..right up to the arrival date otherwise h.sparrows and or starlings are a problem.

Yup, that's an old fashioned Purple Martin house. Looks like one of the ones that pivots down to clean. If you want to host Purple Martins, you'll probably have to update it a bit. Most Purple Martin enthusiasts put their houses on poles with a winch system to raise and lower the house. Also, you'd need to put on a predator guard and be ever vigilant against House Sparrows and Starlings taking over. You can buy Starling resistant entrances that just tap on over the existing hole. But the House Sparrows you need to trap. Do you know if the previous owners ever attracted Purple Martins? If they did, it would be well worth the effort. If they just put it up (as some people do) and let it be taken over by House Sparrows then it may not be worth the effort.