You will need to contact the museum. The tickets are free.
Most (majority) monuments and museums are FREE. I recommend them all.
You can't go before 1pm unless you have tickets through a tour or an employee. My aunt works for the Smithsonian so we were able to get in right when they opened. There were schools there at that time, but there were people lining up for 1:00pm.
You don't need to just turn up unless you want to go before 1pm
You have to contact the Museum. They don't cost anything to get in, I don't believe.
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