I have been searching google all day with no luck even finding the right title to this book.
I would imagine it was published sometime between 1990 and 1998. I am almost 34 (born in 1987) and loved this book as a child.
This book was shaped like a sky scraper – not a usual rectangle! It was a hardcover and all the pages were also board book material. I don’t recall any words or an actual story — just illustrations.
A track ran through the center of the book with a small plastic square that was an elevator you could move up and down the length of the book. The illustrations inside were the many floors of the building carved up into various different shops and businesses. For hours I would pretend to ride the elevator around running errands in the book.
It’s driving me nuts knowing this book existed (my brother remembers it too) but not being able to find anything even remotely like it after hours of searching online. I now have a daughter who I know would enjoy it just as much if I could find a copy. Although honestly just knowing the title and being able to see pictures of it would suffice!
I am pretty sure that I found it for you! The Big Busy Building, published in 1994: https://www.amazon.com/Big-Busy-Building-Board-Book/dp/0843136596