If you missed this - such a shame as it was a brilliant installation, the best I've seen in the Tate Modern:
Doris Salcedo’s Shibboleth was the first work to intervene directly in the fabric of the Turbine Hall. Rather than fill this iconic space with a conventional sculpture or installation, Salcedo created a subterranean chasm that stretched the length of the Turbine Hall. The concrete walls of the crevice are ruptured by a steel mesh fence, creating a tension between these elements that resist yet depend on one another. By making the floor the principal focus of her project, Salcedo dramatically shifts our perception of the Turbine Hall’s architecture, subtly subverting its claims to monumentality and grandeur. Shibboleth asks questions about the interaction of sculpture and space, about architecture and the values it enshrines, and about the shaky ideological foundations on which Western notions of modernity are built.