Urban growth has necessitated the construction of many large, deep basements in city centres. In many places, most notably London and South East England, these basements are founded upon stiff, over-consolidated clay strata. These clays exhibit long-term heave over many years after the construction of the basement structure, producing additional heave-induced soil stresses and movements. However, scarcity of site monitoring data has led to much conservatism in the design of basements subjected to long-term heave loading. This paper presents the results of a series of geotechnical centrifuge tests, which model the three-dimensional heave behaviour of a rectangular deep basement structure underlain by over-consolidated clay. The tests are carried out at a centrifuge acceleration of 100 times Earth’s gravity. A heavy fluid of the same density as the soil is drained from the basement cavity, to model the excavation process in the field. An actuator subsequently applies a vertical load on the structure’s walls to simulate the construction of an over-site development. The model structure is instrumented to monitor the evolution of vertical displacement at various points on the base slab, structural bending strains in the basement slab and in the walls, and the contact pressures between the structure and the soil. The results show good agreement with monitoring data from a site in London where a basement slab was allowed to heave without any building on top for over 20 years. These findings aim to provide guidance on heave magnitude for future construction projects.