That most recently happened in 2017 and they apparently held the tour as usual. You can see people's photos and videos. https://www.google.com/search?q=april+1

That most recently happened in 2017 and they apparently held the tour as usual. You can see people's photos and videos. https://www.google.com/search?q=april+1+2017+%22trinity+site%22 https://www.google.com/search?q=april+1+2017+%22trinity+site... Here's an example of a video by a visitor on that day. https://www.youtube.com/watch?v=aShq03n3i6c https://www.youtube.com/watch?v=aShq03n3i6c