Frobisher Crescent was always intended as a shopping mall containing 16 or more shops with flats above. The City didn’t attempt this in the end. Instead they let if as office facilities for the City University. The top three of the six storeys above ground were converted to their original residential use in 2010, when they were turned into flats by United House and sold off.
There are 23 acres (9.3 hectares) of open space, including 12 acres (4.8 hectares) of public walkway on the podium, and eight acres of landscaped gardens and water features. (I am not sure those numbers quite work, and different sources have different values, but I guess it must give you a general idea at least.)
There is planting in large concrete boxes on the podium and some are as high as a single storey to allow for trees to be grown in them.
The lake covers over 2 acres (0.8 ha), including a spur that passes under the City of London School for Girls before turning to run between St Giles’s square and Wallside.
The water for the lake enters (rather obviously) in a cascade at the east end of the main part of the lake near Brandon Mews and also from fountains in front of the Barbican Centre. It is (less obviously) recirculated again from the section of the lake near the large semi-circular ruin of medieval tower in front of Wallside.