Complex sentence: The oldest buildings on the site, built in the early 1850s, had originally been a residential'district' school of the South Metropolitan Schools District, a Poor Law institution for pauper children from several parishes in south-east London.
Split into simpler sentences: The oldest buildings on the site, built in the early 1850s, had originally been a residential'district' school of the South Metropolitan Schools District. This was a Poor Law institution for pauper children from several parishes in south-east London.