The construction of microstructural bridges and dams within hydrating cement paste has been investigated using a coordinated experimental/computer modeling approach. Bridge building is seen to be critical for the setting process, and of course also for the subsequent development of strength and mechanical properties. On the other hand, dam building is critical in depercolating the capillary porosity, leading to reduced transport coefficients and hopefully enhanced durability. Opportunities for engineering not only the nanostructure of the bridges and dams but also how they assemble at the microstructure level exist and will surely lead to innovative new materials and structures.