Monserrate, Sintra, Portugal, has a long history of English garden making. Beginning with Gerard de Visme's neo-Gothic house and Picturesque garden in the late eighteenth-century, the estate was rediscovered and developed as a botanical landscape garden by Francis Cook from 1856 until his death in 1901. This thesis aims to re-examine the history of the place, both imagined and real, to establish the role of Gerard de Visme and Sir Francis Cook as co-founders and creators of Monserrate. Abandoned through the early decades of the nineteenth century, the garden gained substance as the ruined garden of William Beckford; visited by Byron, in 1809, it was powerfully described in Childe Harold's Pilgrimage. Gerard de Visme was a wealthy English merchant established in Lisbon from 1746 until his departure in 1794. During this time he made four gardens: at two town houses and at the country estates of Bemfica and Monserrate. A relatively unknown figure, his work at Monserrate has been overshadowed by William Beckford, to whom he leased the recently completed house in 1794. Beckford was a short-term resident, occupying the house for two summers, and, as demonstrated here, made no significant contribution to the house or the garden. Nevertheless, Beckford's presence gave atmosphere and brought fame to Monserrate, and this was amplified due to the circumstances which befell the house following his definitive return to England and Fonthill in 1799. Sir Francis Cook, a Victorian millionaire, devoted much of his life to developing Monserrate as a show place, which, together with his famous art collection, would provide for the establishment of a titled dynasty lasting for a further three generations. The gardens contained a huge variety of exotic plants collected by nineteenth century plant explorers and were, in their day, one of the most famous gardens in Europe