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In page Lei Cheng Uk Han Tomb Museum:

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Since the mid-1980s, visitors have no longer been allowed inside the tomb due to conservation concerns. It can instead only be viewed through glass panel at the entrance passage. The tomb is sealed in a temperature- and humidity-controlled environment,[citation needed] and is protected by concrete, waterproofing layers, topsoil, and turf. Following rainwater leakage problems, the tomb was renovated in 2005, with the addition of a canopy to cover the tomb.[4]