And he's had to put in interior staircases because the elevators are so slow.

As a safety measure many women were asked to go up an interior staircase.

The door to the interior staircase was supposed to be kept locked.

Foundation work and other construction are not included; there is room for an interior staircase to descend to a basement.

The tower also included a secret interior staircase - a source of great fun for his young sons.

Another said they couldn't live in a house where the interior staircase was aligned with the front door.

An interior staircase to reach all levels is open to the public.

A modern interior staircase gives access to higher levels.

The interior staircase and all hallways have no windows.

"Important features, like the interior staircase, had been ripped out," she recalled.