Monserrate was first established as a hermitage by the priest Gaspar Preto in 1540. The first house, built for D. Caetano de Mello e Castro after 1718, was ruined by the 1755 Lisbon earthquake. A neo-Gothic house and its landscape garden were built for Gerard de Visme from 1790-93. Sir Francis Cook (Visconde de Monserrate) purchased the ruins and rebuilt them in the present form (1858-1863). The botanical gardens were then continuously developed until his death in 1901. His grandson, Sir Herbert Cook, formed new gardens within the existing framework during the 1920’s.

De Visme employed an English architect, described as “a carpenter from Falmouth,” (identity unknown). Francis Cook commissioned the design of his palácio from James T. Knowles (assisted by his son, Sir James Knowles). The works were supervised by James Samuel Bennet. The garden layout was attributed to Sir Francis himself (1869), though he was assisted by his head-gardener Francis Burt. Later the landscape artist William Colebrooke Stockdale became involved (1873). The second visconde, Sir Frederick Cook, appointed Henri Navel, a French landscape gardener, as director of the park and botanical garden of Monserrate in 1906. In 1923 Sir Herbert Cook enlisted the services of Walter Oates as head-gardener.

Tenants and guests
Monserrate was commissioned by Gerard de Visme and completed by 1793, though he left Portugal in 1791. William Beckford lived at Monserrate from 1794-5 and again from 1798-9. Subsequently the property fell into disrepair and was visited by Lord Byron in 1809, as described in ‘Childe Harold’s Pilgrimage’. During the following half century the ruins were visited and described by many travellers to Portugal. Shortly after work to rebuild the house had begun, Monserrate was visited by Alfred, Lord Tennyson (1859), and later, in 1866, by Hans Christian Andersen. Sir Francis Cook’s son, Sir Frederick inherited Monserrate in 1901 and continued the family tradition of visiting during the late April, May and early June. He entertained the Portuguese king, Carlos I and British monarch, Edward VII, in April 1903. Sir Herbert Cook, grandson of the founder was the last of the Cooks to fully enjoy Monserrate (1920-39). His son, the second Sir Francis, spent his youth visiting Monserrate with his fellow artists, but from 1929 onwards the estate was put up for sale. His last visit was made 1936 and the estate sold in 1946.

Restoration work during the 20th century
Recuperation work began in the late 1980’s. Parques de Sintra, established in 2000 (decreto-lei nº 215/2000, de 2 de Setembro) has carried out an integral recuperation of both house and garden that includes projects for infrastructures (2010) and interior conservation of the house (Chapel, Library, Dining Room, 2010/2012). Work in the garden implemented so far includes ornamental lakes, Mexican garden, rose garden and part of the fern valley. The surrounding landscape and forests and reservoirs are also managed by Parques de Sintra.