Complex sentence: This plan is not yet officially confirmed, but when it is, Riga will consist of 58 neighbourhoods, each with its own centre, its own unique architectural form and landscape, however they are not intended to be a form of administrative division.
Split into simpler sentences: This plan is not yet officially confirmed, but when it is, Riga will consist of 58 neighbourhoods, each with its own centre, its own unique architectural form and landscape. However, they are not intended to be a form of administrative division.