I have seen it posted that the observation deck and the park itself is open 24/7 but the facilities like restrooms and museums are not. I have been there many times and my impression is you can go to the top yourself anytime you want. Only one time there was too much ice on the steep road to the parking lot and they closed the road to everyone.
I heard one of the workers yesterday say the building close at 4pm but your more than welcome to stay and watch the sunset or even the sunrise. Give them a call
More than likely not
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