Some of the earliest examples of concrete slabs were built by Roman engineers. Because concrete is quite strong in resisting http://en.wikipedia.org/wiki/Compression_(physical), but has relatively poor http://en.wikipedia.org/wiki/Tensile_stress or http://en.wikipedia.org/wiki/Torsion_(mechanics) strength, these early structures consisted ofhttp://en.wikipedia.org/wiki/Arch, http://en.wikipedia.org/wiki/Vault_(architecture) and http://en.wikipedia.org/wiki/Dome. The most notable concrete structure from this period is the http://en.wikipedia.org/wiki/Pantheon,_Rome in Rome. To mould this structure, temporary http://en.wikipedia.org/wiki/Scaffold and formwork or http://en.wikipedia.org/wiki/Falsework was built in the future shape of the structure. These building techniques were not isolated to pouring concrete, but were and are widely used in http://en.wikipedia.org/wiki/Masonry. Because of the complexity and the limited production capacity of the building material, concrete's rise as a favored building material did not occur until the invention of http://en.wikipedia.org/wiki/Portland_cement (and developments by the http://en.wikipedia.org/wiki/Edison_Portland_Cement_Company) and http://en.wikipedia.org/wiki/Reinforced_concrete.