Abstract: A modular access chamber, shown generally at 1000, is suitable for providing access to underground services (not shown), such as telecommunications cable systems and the like, and is designed to be supplied in component form, for assembly on site. The chamber may be constructed to be of different depths and is generally rectangular in plan, comprising first and second types of connectable wall portions, 1100 and 1200 and a cover 1300. The wall portions 1100 and 1200 interlock to form a substantially continuous perimeter wall, for example such that the wall portions 1100 each comprise a substantially C-shaped part of the perimeter of the completed access chamber, whereas the wall portions 1200 form substantially linear parts of the perimeter. The cover 1300 has an integral tread pattern 1310 to provide a non-slip surface.