On 12 November 1920, the Italian town of Rapallo witnessed the Kingdom of Serbs, Croats and Slovenes and the Kingdom of Italy signing the Treaty of Rapallo, which determined the post-WWI border between the two countries. From the Slovene viewpoint, Italy gained a third of the Slovene ethnic territory, as well as parts of Croatia (Istria and part of Dalmatia). The demarcation line ran roughly along the watershed between the Black Sea and the Adriatic Sea, along the high mountain range of the Julian Alps in the north, the Alpine foothills in the central part, and along the Dinaric Mountains in the south. On the actual terrain, the border was formally marked with boundary stones and precisely recorded in the maps with the scale of 1:5,000. The border was divided into 70 sectors, which were separated by main boundary stones. Between these main boundary stones, approx. 5,000 boundary stones of a different kind marked the precise route of the border. About a quarter of them have been preserved to this day. The new border altered the lives of people and caused many of them to lose their sources of income. To fight poverty, many turned to smuggling (contraband), which began to flourish. Virtually anything could be smuggled, from flour and meat to cigarettes and matches. Smuggling cattle and horses was the most lucrative activity. Although dangerous, smuggling was a good way to earn a living. Despite the agreement on where the border should be, both sides began fortifying it, fearing potential future border disputes. Such activities were first undertaken by the Italians in the 1920s. In 1931, they initiated fortification work on a greater scale, constructing a large number of un- der- and above-ground fortifications and barracks, which formed the Alpine Wall. On the Yugoslav side, a similar initiative was given in the mid-1920s, but no major fortification efforts were realised before 1935, when the Rupnik Line construction began. The defence line never served its purpose as it had been abandoned even before Italy attacked Yugoslavia in the April War of 1941. The remnants of Italian and Yugoslav fortifications are still visible today and have tourist potential. At the beginning of WWII, the Italians signed a new border agreement with the Germans on 8 July 1941 in Berlin, following the occupation of the Kingdom of Yugoslavia. The northern part of the Rapallo Border still served as the national border (between Italy and Germany), while its southern part became Italy’s internal regional border. After WWII, the border between Italy and Yugoslavia moved towards the west, much closer to Slovenia’s western ethnic border. In addition to material remnants (fortifications, boundary stones), the border, albeit used for only 25 years, has echoed in the Slovene regional affiliation, and is still partly reflected in various administrative divisions.