sentences:  That building, which now constitutes the eastern end of the department, was considerably extended in the 1930s, with the construction of new lecture theatres and laboratories.In the 1980s, the building was further extended with the addition of a top floor to provide a new laboratory for computing, remote sensing and geographical information systems.In 1999 the department expanded again, to occupy two floors in an adjacent building where new laboratories, seminar rooms and offices are housed.