TV Guide PBS America Friday

Criminologist David Wilson investigates the mysterious death of Russia's first dictator, beginning by analysing rumours that the man who used terror to rule his huge empire may have been strangled by enemies in his court. The trail takes Wilson across Russia and back to London, where he explores a story of intrigue surrounding England's Queen Elizabeth I, uncovering clues along the way which lead to a final twist in the tale

A look at the relics found in the tombs of China's Han Dynasty. The era is generally considered the golden age of ancient China, rivalling the Roman empire for international power, and has been a defining influence on the country's cultural identity ever since. The programme examines how the emperors arranged to have their dead bodies mummified in the search for immortality and looks at a newly discovered version of the famous terracotta army

With access to the first nationwide survey and state-of-the-art drones mapping the Great Wall of China, this documentary offers new evidence that reveals its extraordinary magnitude, rewrites its millennia-long history and decodes its complex signals system. Using cutting-edge chemistry, the programme also finds out what has kept the wall standing for so long - a simple cooking ingredient found in kitchens across the world