This week's Good Facility is a cycling and walking underpass in the London borough of Lewisham.
The underpass is a renovated tunnel under the railway line into London Bridge station, which was formerly a road (see Streetview link!). It is now filtered, with bollards at the entry points at either end, with a (very) wide cycleway with separated footway. This underpass path also connects with (the nearby) Quietway 1.
You can read more about this underpass on the Ranty Highwayman blog.