The Auge, meaning "a U-shaped valley, a trough", fortified right after the city's foundation displays the Rue des Forgerons (blacksmiths) as an example of the craftsmanship in fashion back in the olden days.
Protection from potential invaders was of paramount necessity: a fortified gate led to the Central Bridge and the Bern Bridge, an imposing tower called Muggan (Mosquito) until 1838. The first fortification wall stretched between the Bern Bridge and the Augustinian Friary across what, at a later date, became a row of houses westernbound of the street named Rue d'Or and the second wall running alongside the Sarine River.