Complex sentence: The district is on St Armand's Key, adjacent to Lido Key and is centered around Harding Circle, in the center of the key around which the retail center of the key is located.
Split into simpler sentences: The district is on St Armand's Key, adjacent to Lido Key. Roughly, the disrict is centered around Harding Circle, which is in the center of the key and around which the retail center of the key is located.