One thing I like about Washington D.C. is the big museums on the mall all have free admission.
In London (when I was there) some were free (eg: National Gallery, Imperial War Museum), others (such as the V&A) had voluntary admission prices, where there was a suggested fee to enter, but if you said you'd rather not pay you still were allowed in...they just wanted to guilt you into offering a donation, esp. if you were a tourist (and before everyone calls me cheap, I did pay the suggested donation at the V&A, but many didn't in the line to go in, and one chick I was flirting with who worked at the V&A said she always told her friends to decline the donation).
Now "free" means supported by tax dollars so as to available to be used by everyone.
I haven't been to the ROM for 25 years, but I might go take another look.