Complex sentence: Grotton is a residential suburb of Oldham, mostly developed since the 1930s whose main claim to fame is that it used to be home to an open-air swimming pool, Grotton Lido.
Split into simpler sentences: Grotton is a residential suburb of Oldham, mostly developed since the 1930s. Grotton's main claim to fame is that it used to be home to an open-air swimming pool, Grotton Lido.