据史书记载,公元前227——216年间,秦始皇几次遭到行刺,引起他高度警觉。因此在始皇35年,在都城咸阳之南兴建阿房宫,采用大量磁石建造了一个巨门——“磁石门”,以防隐藏利刃者进宫行刺。这是我国历史上最早的应用磁石吸铁特性所建造的警卫装置。 According to historical records, during 227-216 BC, the Qin Shi Huang was assailed on several occasions, arousing his vigilance. Therefore, in the first emperor 35 years, in the capital city of Xianyang built A Fangong, using a large number of magnets built a giant door - “magnet door” to prevent the hidden knife into the palace thorn. This is the earliest history of China's magnet magnet attraction built by the security device.