A barbican or ravelin is a medieval defensive structure that served as support for the surrounding wall or any tower or fortification, advanced and isolated, located above a gate, postern or bridge that was used for defensive purposes. The barbicans were usually located outside the main line of defense and connected to the city walls by a fortified road.

Such a fortification was often just an embankment attached to the wall next to the most vulnerable area of ​​a castle or stronghold. This defensive system was already widespread in the early Middle Ages practically throughout Europe also due to its relative simplicity of construction.

Having been aimed at the defense of military constructions, there are exceptions in which the barbicans come as a defense of civil structures rather than support. The explanation is that given the poverty of small towns, a similar embankment represented a simple, quick and inexpensive constructive solution.

In the century with the improvement of military tactics and artillery, the barbicans lost their importance. However, some were still built in the 19th century.

Some notable barbicans are Warsaw and Krakow, both in Poland.

Barbican comes from the Hispanic Arabic 'báb albaqqára' (cowboy door). It is a term that is used in several European languages: French, Italian (barbacane), Portuguese (barbacã) and English (barbican). In a very archaic form, the barbicans were also the vertical loopholes on the castle walls to be able to hit the enemy while staying under cover. In fact, the term has in the past been used to designate other types of fortifications.

Due to the very nature of the embankment, today some area, often very small or far from inhabited centers, has taken the name of barbican. Only, these toponyms are located where a barbican formerly arose in the first meaning explained.

As an example, in Italy there are the following barbicans: