At the age of twenty John Campbell inherited the earldom of Breadalbane from a distant cousin. He also became the owner of Taymouth Castle, the family seat, and the vast surrounding Perthshire estates. By the age of forty he had already spent well over £50,000 demolishing William Adam's eighteenth-century house and creating a magnificent Gothic revival castle. He continued to spend lavishly on both building and agricultural improvements — particularly in planting larch and Scots firs on land previously considered barren.