Hotel Georgia and Tower

 https://en.wikipedia.org/wiki/Hotel_Georgia_(Vancouver) The stump hotel building doesn't even have 15 floors, when it should have been 30, even back in 1927.

https://en.wikipedia.org/wiki/Hotel_Georgia_(Vancouver)#The_Private_Residences_at_Hotel_Georgia

https://upload.wikimedia.org/wikipedia/commons/4/42/Private_Residences_at_Hotel_Georgia_2015.jpg Another 48 story shortfall. However, the building still might be equivalent to having 51 floors.