Complex sentence: The fort is adjacent to the Venetian Isles community, now legally within the city limits of New Orleans, Louisiana, although some miles distant from the city when first built and still a considerable distance from the main developed portion of the city.
Split into simpler sentences: The fort is adjacent to the Venetian Isles community, now legally within the city limits of New Orleans, Louisiana. This community was some miles distant from the city when first built and is still distant from the main developed portion of the city.