Complex sentence: In spite of owning a large mansion in that area, he developed a passion for building, embarking on the project of re-creating the lost castle of Eaton Bray on some land bequeathed him by his mother.
Split into simpler sentences: In spite of owning a large mansion in that area, he developed a passion for building. He embarked on the project of re-creating the lost castle of Eaton Bray on some land bequeathed to him by his mother.