It looks as though an exploratory dig has begun next to the County Hall museum.
The architect presumably needs to check the lay of the land before drawing up the designs for the proposed lift which would go down to the basement and up to the first floor
(P.S. as commenters have said this is the archaelogical dig before the architect gets a look in)
What an amazing amount of prep work …. WOW!
I think around here they are obliged to call in archeologists before any major construction work?
There is a sign by the digging saying 'Oxford Archeology' and an emergency phone number.