The first great Palladian mansion to be built in Ireland (1722), Castletown House faces south over the Liffey Valley towards the Wicklow Mountains. The central building (13 bays), was designed by the Florentine Alessandro Galilei (1691-1737) and is connected to the wings by two curved colonnades. The most outstanding room is the Long Gallery. Its Pompeiian style decoration, predominantly bright blue combined with red and green, was designed around 1775 by two English artists, Charles Reuben Riley and Thomas Ryder.