In Nairobi, the speed of urban growth is producing a parallel threat of architectural failure: in a recent spate of tower block collapses, many have died. Nairobians describe collapsed tower blocks as “fake,” referring to ideas of the counterfeit, as well as anxieties about morally suspect economies. Simultaneously, state-led development is re-envisioning Nairobi as a “world-class” city of spectacular infrastructure and gleaming high-rises. Though seemingly disconnected processes, the two are deeply entangled. Building on Africanist debates about the power of the double and the relationship between the surface and the underneath, I explore this superficially sleek but materially fragile landscape through a lens of “gray development,” complicating standard distinctions between the informal and the formal to uncover the underneath of Nairobi’s world-class fantasies.