What are the characteristics of Ganling in Tang Dynasty?

Tang Ganling is the only female emperor in the history of China. Wu Zetian was buried with her husband Tang Gaozong. After Qin and Han Dynasties, most emperors and empresses were not buried together, but the tomb of the two saints of the Ganling couple was unique. In the ancient society of China, where men were superior to women, the debate about the evaluation of Wu Zetian's life activities stirred for thousands of years, which had a far-reaching impact on China's cultural blood. Gan Tang Mausoleum is the only double-walled mausoleum found in the imperial tombs of the Tang Dynasty. Its inner city symbolizes the imperial city of Chang 'an, the capital city, and its outer city is equivalent to Guo Cheng where officials and natives live, reflecting the overall pattern of the ancient capital of China at that time. Gan Tang Mausoleum is also the only royal mausoleum of the Tang Dynasty that has not been stolen for thousands of years. Its underground tunnel number lettering masonry has been found, and there are thin waist iron pads and tin iron ingots unearthed, which is a unique value that ordinary tombs do not have.