Complex sentence: Santa Fe is the traditional downtown of the city of Bogotá, the urban area of what once was Bogotá's total main urban area known as "Santa Fe de Bogotá" with its traditional neighborhoods.
Split into simpler sentences: Santa Fe is the traditional downtown of the city of Bogotá. This area once comprised Bogotá's total main urban area, and was known as "Santa Fe de Bogotá" with its traditional neighborhoods.