Johnstone Castle belonged to the Houstouns of Milliken, who acquired the estate of Easter Cochrane in 1773. The original structure was substantially enlarged in 1771 and 1812 by George Houstoun, who had the structure remodelled in a castellated style complete with a turret at the left hand of the front elevation, possibly by the architect James Gillespie Graham.
The most notable features were barrel vaulted rooms in the ground floor. Externally in addition to the battlemented decoration there was a rope-styled string course. Although the castle and policies were considered particularly picturesque, the continued growth of the town of Johnstone reduced its size and the estate had largely disappeared by the start of the 20th century. Much of the house was demolished in 1950, and most of the remainder of the grounds was purchased by the local authority for housing in 1956.
Today all that remains is the central square tower along with a crow-stepped bartizaned section of an older date.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.