They started taking down Randall Tower yesterday. 1 and 4 are from this afternoon, 2 and 3 from this morning.
Hi-Ray Hall, a little cinder block building its former location behind Union South in the last photo, was knocked down last week. There was a short PDF about it here a few weeks ago. There's a little info on the UW map page. I remember reading that it was built as private apartments in the mid 60's by the Hi-Ray Co. It was not profitable and sold to the UW within a 2-3 years and it might have been a dorm for a few. Otherwise it's been overflow office space since.
It looks like they'll be taking down Union South next week, which happens to be our spring break.