Derry's walls were originally built by the Irish Society between 1613 and 1619. They were built with the intention of protecting the Scottish and English planters that had moved to Ulster as part of the Plantation of Ulster that had been established by James I. It was a direct consequence of the previous settlement being destroyed by Irish chieftain Cahir O'Doherty during O'Doherty's rebellion. As a result of the building of the city's defences by the Irish Society, which was a consortium of livery companies based out of the City of London, the city was officially renamed Londonderry in the 1613 royal charter. This is what has subsequently led to the naming dispute for the city and county of Derry/Londonderry.
The walls are at the centre of the historic city of Derry and within them are a number of Derry's most important landmarks including the Apprentice Boy's Hall and St. Columb's Cathedral.
The walls are about 1 mile in circumference and contain many of the city's most important landmarks. The entire length of the walls is fully accessible on foot. There are seven gates in total, four of which were built at the same time as the walls themselves and three were added later.
References:The Château de Foix dominates the town of Foix. An important tourist site, it is known as a centre of the Cathars. Built on an older 7th-century fortification, the castle is known from 987. In 1002, it was mentioned in the will of Roger I, Count of Carcassonne, who bequeathed the fortress to his youngest child, Bernard. In effect, the family ruling over the region were installed here which allowed them to control access to the upper Ariège valley and to keep surveillance from this strategic point over the lower land, protected behind impregnable walls.
In 1034, the castle became capital of the County of Foix and played a decisive role in medieval military history. During the two following centuries, the castle was home to Counts with shining personalities who became the soul of the Occitan resistance during the crusade against the Albigensians.