French builder François Coignet built the first iron-reinforced concrete structure in 1853-55, English builder William Wilkinson reinforced concrete with a documented understanding of tensile stress in 1854, and French gardener Joseph Monier patented reinforcing techniques from 1867 onward that became the ones most widely licensed and developed afterward, so historians differ on whether priority belongs to the earliest build, the earliest tensile understanding, or the most influential patent.
What would resolve this A surviving technical record proving which of Coignet, Wilkinson or Monier first understood and deliberately exploited concrete's tensile weakness, rather than simply embedding metal for another reason, would settle whose work counts as the true invention.
OpenHistory of structural and architectural engineeringReinforced Concrete (Wikipedia)