Los Angeles, George C. Page Museum of La Brea

I you're visiting LA and want a bit of natural history right in the middle of LA, you can't go past this museum. It's fascinating for adults and children alike as it's hands-on, indoor-outdoor setup keeps everyone interested! It cost less than $20 for our family of 5 (one is a baby, who I don't think they charged for) and kept us amused for hours. It's a few blocks' walk form the nearest metro station and is an odd little Oasis in the middle of a huge city. The tar 'pits' (actually pools of bitumin) have woolly mammoth statues which are animatronic, which the kids love, and just to see this natural product oozing from the ground to this day, in the middle of LA is fantastic. The kids (and adults!) can see if they would be able to pull themselves out of the tar at one of the displays; there's a movie on the history of the pits; you can see volunteers working on bones pulled from the tarpits which range from mouse toe-bones through to the enormous pelvic bones of fully grown woolly mammoths - and there's also a free tour which is very informative (though not suited to very small children as it's a tad scientific & long). We'll definitely go there again when we're in that part of the world!