Complex sentence: It was well known for its gardens in the 18th century but was demolished around 1840 as part of the development of the Bridgewater Canal, having been noted to be in poor condition in 1807 and by that time was leased to various poor tenants.
Split into simpler sentences: It was well known for its gardens in the 18th century but was demolished around 1840 as part of the development of the Bridgewater Canal. It had been noted to be in poor condition in 1807 and by that time was leased to various poor tenants.