Easy to get to by Subway, there's lots of stations around the Financial District so it's hard to miss. The museum itself is amazing, it takes a few hours to get around because you want to read everything and take it all in.
The museum goes underground to where the current fountain memorials are which is a great architectural touch, it's absolutely fascinating.
There are staff on hand all around the museum to talk more extensively about the exhibits and photos are allowed in some areas.
We could've easily spent a lot of time in here but it's a shame people feel the need to take selfies/photos of everything. It should be treated as a memorial.
Thank you to the member of staff outside who also kindly went back in to the gift shop for me (since I wasn't allowed to go back in myself) to get me a very special keyring!