 He also purchased land on the outskirts of the city, where he constructed a pleasure garden, concert hall and coffee house, known as the New Gardens.Profit from this venture was used to construct the Rotunda Hospital, designed by Richard Cassels, which opened on 8 December 1757.Mosse spent a considerable amount of his personal fortune on this venture, falling into debt, and eventually being imprisoned for indebtedness, although he escaped through a window and went into hiding in Wales.