Original Avernus City
Silicon Knights described the last 6+ months of Blood Omen's development as including a dramatic increase in the quality of the game assets ("40 in-game characters are increased to 190, 40 tiles sets are increased to over 600"). The change in the appearance of the city of Avernus between 12 July 1996 and the game's release in October of that year is one of the most obvious examples of that shift.
This is the city as it appears in the 12 July build:
This is the city in the final version of the game:
Virtually every aspect of the production design has been improved. However, at the same time, the size of the area seems to have been decreased substantially as a result. As discussed in more detail in Alpha and Beta Versions, Avernus originally consisted of 100 map sections. It was temporarily reduced to 27 for the 12 July build, and increased back to 48 by the time the game was finished.