On July 19, 1900, the first line of the Paris metro opened to the public at exactly 13 o'clock, offering eight stations to the city's inhabitants. The trains running under the paving stones from Porte Maillot to Porte de Vincennes were constructed with wooden carriages, a standard material for railway construction at the time. The construction of the line had started on October 4, 1898, under the direction of engineer Fulgence Bienvenüe. The project, adopted by the Municipal Council in 1896 and declared of public utility by the law of March 30, 1898, aimed to accommodate visitors of the World's Fair announced for 1900. Bienvenüe led the project with a team divided into three geographical sections: east, west, and center, each entrusted to a bridge engineer. The speed of the construction was remarkable compared to current standards for major underground works in Paris. The first signs of warning appeared in October 1900, just three months after the opening, when a short circuit caused a fire at the Concorde station, resulting in a collision with the following train and causing 38 injuries. However, these incidents did not lead to immediate changes in practices. On August 10, 1903, a fire on line 2 North caused the death of 84 people at Couronnes and Ménilmontant stations. The disaster occurred when train 43, composed of eight wooden carriages, including two motor cars, experienced an electrical short circuit on one of the motor cars. The wooden carriages caught fire within minutes, and the fire spread through the tunnel, filling the Couronnes and Ménilmontant stations with smoke. The lighting failed as the electrical wires melted under the heat, leading to darkness and panic. Passengers rushed toward what they thought were exits and perished from suffocation or were crushed against the walls. This event became the worst accident in the history of the Paris metro network. The fire prompted a major overhaul of the safety systems of the metro's operation, leading to the segmentation of the electrical supply in case of incidents, the implementation of an independent emergency lighting system, and the planned abandonment of wood in favor of metal for carriages. The transition to metal carriages did not happen overnight but led to the rapid abandonment of wheelset cars in favor of longer bogie cars. From 1908 onwards, metal carriages with a remote control system known as Sprague-Thomson were introduced. The network definitively shifted to metal, a material considered incompatible with underground operations that the capital had just invented eight years earlier. The disaster also imposed a rule still in force today in a modernized form: each station must have a minimum of two distinct exits for passengers, a requirement directly born from the evacuation difficulties observed at Couronnes. The Paris metro, often cited as an example for its reliability, owes part of its current safety standards to this August night in 1903 when wood showed its limits against fire.