This is 55 Ludgate Hill.
The BT Tower on Lionel Street, next to 55 Ludgate Hill.
Number 55 Ludgate Hill is an early-mid 20th century office block on the corner of Ludgate Hill and Lionel Street. The building is of four storeys with seven-bays to Ludgate Hill and five-bays to Lionel Street, the entrance is on the corner of the building. It is built of dark brick with lighter brick panels and balconies to the first floor windows, except for the one above the entrance.