Hart Industries is often represented by the above photo. A closer look shows that the real building has a different street number to Hart Industries.
Early in the series Hart Industries is located in a multi-storey buiding with entry via a stairway (left). This composite photo shows the lower levels of the building.
It is still a multi-storey building, but entry is via a forecourt at ground level, and a lift is taken to Jonathan's office on the sixth floor. Note that the Hart's Rolls Royce has just pulled up at the kerb.
[Click photos to see full size.]
Signs of Hart Industries as shown in the Pilot (left) and later in the series.
Entry to the building later in the series.
The first photo shows the lift to Jonathan's office. In the second photo, Jonathan is walking from the lift to the glass entry doors.
The first photo shows Jonathan at the entry doors and the other photo shows the view into the forecourt from these doors.
Continuity problem: the windows in Jonathan's office
Jonathan's office is always shown with round windows - which is impossible with the exteriors above.