On my way back to work I spotted a tower crane I hadn't noticed before and checked it out. Turns out to be for the second Mason St Glide housing project. You might recall that the first of these (125 Mason) is also the offsite affordable housing for the Millennium Tower development.
This is
149 Mason, which will be studio apartments and services for formerly homeless:
It will look like this:
Source:
glide.org
It sits right next to the aforementioned and recently completed
125 Mason:
I wish I had taken more shots of it and could have gotten a better angle because it's yet another example of the interesting architecture going up throughout the Tenderloin.