The town across the frontier is named after a wall, and the kind of wall matters. A contravallation is the line a besieging army throws up facing the place it is trying to capture. La Linea de la Concepcion is named after the side of a siege work that pointed at Gibraltar. About 15,000 people now cross that same ground in the opposite direction every working day, to go to work on the Rock. This is how the wall got there, who demolished it, and why the name outlasted every stone of it. Spain had just failed to take Gibraltar again. The siege of 1727 ended without result, and the conclusion drawn in Madrid was that the isthmus had to be held permanently rather than occupied each time a war started. An order went out on 2 November 1730 to the Marquis of Verboom, Philip V's director of engineers, to fortify the neck of land. Work began the following year. According to the record of the [Lines of Contravallation of Gibraltar](https://en.wikipedia.org/wiki/Lines_of_Contravallation_of_Gibraltar), Fort San Felipe went up at the western end on the bay side with 28 gun positions and room for up to 600 soldiers, and Fort Santa Barbara at the eastern end on the Mediterranean side with 24 gun positions and a pentagonal arrowhead plan. Between them ran roughly 950 toises of fortification, about 1,700 metres, built as a redan line with five triangular bastions named Santiago, San Carlos, San Jose, Santa Mariana and San Benito. The whole thing stood about 1,800 metres from the Rock and was finished in 1735. The isthmus is barely over a kilometre wide at that point. That is the entire military logic of the place: a line that short, anchored on two seas, closes Gibraltar off by land completely. Two kinds of wall get built around a besieged town, and the distinction is not decorative. [A contravallation](https://en.wikipedia.org/wiki/Circumvallation) faces inward, towards the fortress, to contain the garrison and tighten the blockade. A circumvallation faces outward, to hold off an army coming to relieve it. Spain built the inward facing one. So the name on every road sign, every bus timetable and every football shirt in that town is the technical term for the side of a siege wall that pointed at the Rock. It is an unusual thing for a town of 64,000 people to be called. They worked as artillery positions. The batteries on the Lines fired the opening shot of the Great Siege in July 1779 and bombarded Gibraltar through the Grand Assault of 1782. They did not work as a siege. The Great Siege ran from June 1779 to February 1783, the longest in British military history, and Gibraltar did not fall. Nearly fifty years after the first order went out, the Lines shelled the Rock for three and a half years and changed nothing whatsoever about who held it. > The wall was built to take Gibraltar. It was demolished by Gibraltar, with the permission of the people who built it. On 14 February 1810 British engineers under Colonel Sir Charles Holloway blew up the Lines. Spain agreed to it. Both were by then fighting Napoleon, and the fear was that a French army moving south would find a ready made fortified position sitting across the isthmus, pointed at Gibraltar, with the work already done. So the besieging wall came down at the hands of the besieged, by mutual consent, because of a third party. The [ruins of Fort Santa Barbara](https://en.wikipedia.org/wiki/Ruins_of_Fort_St._Barbara) have been excavated, are owned by the municipality of La Linea today and were declared a Bien de Interes Cultural, a national cultural monument, in 1994. Fragments of San Felipe survive as well. | Date | What happened | | 1727 | Spain's siege of Gibraltar fails again | | 2 November 1730 | Philip V orders Verboom to fortify the isthmus | | 1731 to 1735 | Forts San Felipe and Santa Barbara and the line between them are built | | July 1779 | The batteries fire the opening shot of the Great Siege | | 1782 | The Lines bombard Gibraltar during the Grand Assault | | 14 February 1810 | British engineers demolish the Lines, with Spanish consent | | 17 January 1870 | Segregation of La Linea from San Roque is approved | | 1883 | The name La Linea de la Concepcion is first officially recorded | | 1913 | La Linea is granted city status | Blowing up the Lines left a gap, and that gap is why the modern map looks the way it does. The Treaty of Seville had already fixed a neutral zone between the two sides in 1729, set at 600 toises, which is roughly two cannon shots. After 1810 there was a band of flat ground with a demolished Spanish fortification at one end, Gibraltar at the other, and no flag on it. How it stopped being neutral is still argued about. Britain asked Spain in 1815 for permission to put quarantine barracks on the neutral ground during a yellow fever epidemic. Spain agreed. The barracks were not removed afterwards. An airfield went in on the same isthmus from the 1930s, and Spain's case lists that construction among its objections. The two cases are set out in t