Complex sentence: For many years, it has been a symbol of the power and prosperity of the old Hanseatic city, and as Germany's third largest church it remains the tallest building of the old part of Lübeck.
Split into simpler sentences: For many years, it has been a symbol of the power and prosperity of the old Hanseatic city. It is Germany's third largest church and occupies the highest point of the old part of Lübeck.