有门的屏障 · THE BARRIER WITH DOORS
A Wall Worth Crossing — Europe · The Alps
阿尔卑斯把意大利与北欧隔开——隔得如此彻底，以至那寥寥几个山口足以左右战争。公元前 218 年，汉尼拔用约十六天，把约三万人马和三十七头战象拖过雪山，从背后突袭罗马。
山的屏障不只阻挡军队，更把他们漏成一束。正因为只有布伦纳、圣伯纳等少数垭口可通，扼住它们的人便扼住了南北之门。两千年来，商旅、朝圣者与军团都从同样的几道豁口穿行，守口的城镇因此富庶。
The Alps wall off Italy from northern Europe — so completely that the handful of passes through them have decided wars. In 218 BCE Hannibal hauled an army of ~30,000 men and 37 war elephants over them in about sixteen days to strike Rome from behind.
A mountain barrier doesn't just stop armies; it funnels them. Because only a few cols — the Brenner, the St Bernard passes — are crossable, whoever holds them holds the door between north and south. Trade, pilgrims and legions all threaded the same notches for two thousand years, and the towns that guard them grew rich.