Also (or later) known as Hungerford Stairs, these were near the south-east end of what is now Charing Cross train station, where Hungerford Bridge begins. Hungerford Stairs can be seen on this 18th century map.
The overlays that highlight 17th century London features are approximate and derived from Wenceslaus Hollar’s maps:
Open location in Google Maps: 51.507267, -0.123457
Hungerford Stairs in 1746 was Charing Cross Stairs in the 1660s
Chart showing the number of references in each month of the diary’s entries.