In July 1995, the Tate Gallery commissioned the Unit for Architectural Studies to carry out a study of the spatial design and patterns of space use in the existing Tate Gallery, as an aid to evaluating proposals for a new masterplan with a basement level entrance.The study was to comprise four stages: computer modelling and analysis of the existing layout using 'space syntax' techniques; observations of current patterns of movement and space use; correlation of the spatial analysis and observations to provide a detailed picture of how the Tate is currently working; computer simulation of the new design proposals in light of findings of the study in order to evaluate the likely effects of changes in the layout on the pattern of movement and space use in the Gallery.The observation study was carried out during the week of 7th August. Because Room 20 was closed at this time until 4th September, further observations in and around this space were carried out after this date to see how far the closure had affected the pattern of movement and space use. The lower ground gallery was not open during the first observation period, and was therefore also observed during this later period.