Huge Panorama of London in 1845 (ianvisits.co.uk)
Ian explains more on the origins:
An original document is quite rare and when one comes up for sale, they usually go for prices that would deplete my wallet. Fortunately, a reprint made for the newspaper's 150th anniversary tends to be more affordable, and I recently acquired a copy – which has been annotated with additional explanatory text. The scanned copy is huge (6GB) – sadly too huge for my feeble computer to cope with, but I have managed after some pleading with the laptop to deploy a moderate sized version.
The drawing itself is presented as two separate drawings, and I have joined them together in the middle to form a single long strip. Enjoy!