Complex sentence: Trinity is a leafy district of northern Edinburgh, Scotland, once a part of Greater Leith (itself a part of the city since 1920) it is one of the more desirable neighbourhoods in Edinburgh.
Split into simpler sentences: Trinity is a leafy district of northern Edinburgh, Scotland, once a part of Greater Leith (itself a part of the city since 1920). It is one of the more desirable neighbourhoods in Edinburgh.