After a losing hope about the state of mathematics in the world, I was delighted to learn about and visit the National Mathematics Museum (MoMath)in New York City. Located at 11 East 26 Street, it opened to the community in December 2015. It is worth the trip!
From the Pi symbol door handles to the hologram engraved art work, each inch of this museum is filled with interesting sites and many interactive activities! I loved riding a bicycle with square wheels. It was a little hard on the rear! But fun.
We three adults were having as much fun as the children. There are two floors of activities that parents and children can work on together. Some are math and logic problems to solve. Others are just fun activities like watching your arms branch out into fractals in a living tree exhibit.
I wish I can tell you my favorite activity, but I cannot since so much of it was great fun.
There is also a room where temporary exhibits are housed. When we were there it was unbelievable math art that has to be made through 3-D printers. And fantastic origami art.
The gift shop is packed with educational games and activities to buy. More important this museum is open every day except for Thanksgiving! Need something to do with your children school age and older, go here! There are events and activities listed on its website which I put below.
It is an easy walk to Madison Garden Park where you can sit for a bit and people watch, take great photos of the flatiron building and buy lunch or a snack.
Being there gave me hope. There are parents and children and grandparents interested math and learning. I did not see one frown while there, I just saw adults and children intrigued by what they were seeing and learning while having an adventure at the MoMath!
Www.momath.org
zicharonot 
Sounds great for my grandsons—I wonder if my daughter and son-in-law know about this museum.
It is wonderful. A great place for a few hours and lots of good eating near by.
Eating is never the problem in NYC! My grandsons love math and the kinds of puzzles and problems you described, so I will definitely suggest this for our next trip to visit them.
Great. We loved it.