Reinforced concrete was invented during the second half of the 19th Century. Besides the need to substitute wood for gardening and recreational use, the main driver was the need for an economic and fireproof building material. The development of modern cement and steel during the first half of the 19th century made this invention possible. During the 1850s 1860s, two French horticulturalists, Lambot and Monier, started very empirically to build planters and other appliances with cement reinforced with iron or steel mesh. Lambot took a patent in 1855, and Monier a series of patents during the 1860s and later. In parallel, people with closer connections with the construction industry started to develop floor systems associating cement with iron or steel beams, in most case with the intention to protect steel from fire: Wilkinson in England, F. Coignet in France, Ward and Hyatt in both the USA and England. After the early works of these pioneers, this invention was widely developed in some countries, in particular in Germany by Freytag, Wayss, and Koenen, in France and Belgium by Hennebique, and in the United States by Ransome. In the early days, the construction industry establishment was skeptical about this strange association of cement or concrete and steel, and theoretical approaches started only in 1886 with the works of Koenen. They were followed by those of E. Coignet, Tedesco, Considere, Morsch and others. It is in the early years of the 20th Century that a theory shared by most scientists and practitioners started to appear, along with the first codes. This paper presents this period of invention and early developments of reinforced concrete, with a global view, on the basis of internationally available literature.