I am quite surprised nobody has ever gone here and reviewed this on Yelp. It's been open to the public for as long as I can remember. My mom has volunteered here for about that long as well.
If you're a fan of Victorian homes, local history, or even just history in general then you should definitely check out the Petersen House. It's just as beautiful on the inside as it is on the outside.
Unfortunately, it's closing to the public VERY soon because the city just can't afford to keep it running... but they should re-open it around Christmas time for Danish Christmas. So if you aren't lucky enough to swing by in the next week or so... come back around Christmas!