Imphal Peace Museum - https://goo.gl/maps/bXs5PU7tvJE3JukA6
Here's what comes to mind...
* Mutter Museum in Philly (http://muttermuseum.org/) Awesome victorian medical curiosities
* Museum of Questionable medical devices in St Paul (http://www.museumofquackery.com/). Exactly what the name implies. Really interesting for skeptics.
* Wagner Free Institute (http://www.wagnerfreeinstitute.org/), in Philly. This is victorian-era science museum focusing on natural history. Interesting selection of specimens and a magnificently preserved victorian lecture hall.
* Bata Shoe Museum in Toronto (http://batashoemuseum.ca/). Shoes are actually interesting in historical context!
* Johnstown Flood Museum (https://www.jaha.org/attractions/johnstown-flood-museum/) This is in western PA, about 1.5 hours east of Pittsburgh. Dedicated mostly to the flood of 1889 which shaped the history of this town, as well as the flood of 1977.
* National Electronics Museum (https://www.nationalelectronicsmuseum.org/) This is a short distance from the BWI airport.
The Cryptography Museum nearby is also great.
That being said, I believe it is fair to say that I had a better experience than wife+kids at two of my favourite niche museums - the Grimeton spark gap transmitter in South Sweden and, all-time favourite - the museum of submarine cable in Porthcurno, Cornwall, UK.
Everybody loved the Ramones museum in Berlin-Kreuzberg, though.
1. The American Sign Museum - https://www.americansignmuseum.org/ - Cincinnati, OH. Dedicated to preserving neon signs from across America 2. The International Museum of Surgical Science - https://imss.org/ - Chicago, IL.
For the moment there's an undocumented map you can view here (using my datasette-cluster-map plugin) https://www.niche-museums.com/browse/museums
I stumbled across this hobby a few years ago. Whenever I'm in some place new, I run a search on google maps for "museums" and try to find the smallest, most niche topic possible.
It's a pretty small time commitment - a small museum can often be explored in 30-60 minutes - and it's incredibly rewarding.
The smaller the museum is, the more likely you'll meet the person who set it up. And that's guaranteed to be a great conversation no matter what the subject of the museum is.
A couple of months ago I started a website to share details of the museums I've explored. So far I've managed to post a new one every day, and I've still got a backlog of about 50.
https://www.niche-museums.com/