Sky History 2 Wednesday

Massive megalithic structures and reported discoveries of towering human-like skeletons, contemplating whether they reveal that the world was once inhabited by giants

Experts investigate whether the US military has a secret space programme, as well as evidence suggesting alien races have been in conflict for millennia

Alice Roberts explores the Georgian era in Bristol, taking a horse-drawn carriage ride, sampling backstreet gin, and discovering the story of the world's first chocolate factory

The Holy Grail - coveted by everyone from Roman Emperors to Adolf Hitler, this sacred object is said to hold incredible powers

Treblinka, Majdanek and Sobibor, the camps used in Operation Reinhardt, a murder campaign in which the Nazis murdered almost two million people over two months in 1942 and 1943

Experts question whether extraterrestrials could have helped humans build ancient structures, and if standing stones in Carnac, France, were a GPS system for ancient spacecraft

The suggestion that some animals may have been planted on Earth by aliens as part of an experiment to shape life on Earth

Garth Barnard investigates the Baker's Creek aviation disaster in Australia in 1943, when 40 American servicemen were killed when their B-17 bomber aircraft crashed

Garth Barnard investigates the likely cause of an accident in Nebraska in 1944, when a transport plane crashed during a violent storm

Documentary investigating almost every UFO and alien sighting ever recorded, beginning with the history of HG Wells' The War of the Worlds

Douglas Latchford was regarded as a go-to expert in Khmer antiquities. However, an investigation saw his world crumble

Experts analyse the remains of two Viking boats, that were filled with dead bodies

A look at UFO sightings, terrifying abductions and other bizarre occurrences, casting new light on historic cases

Helen Skelton and Alex Langlands join a dig at Elsyng Palace, one of nearly 60 royal residences owned by Henry Vlll and one of his favourite homes during his last decade

Professor Alice Roberts explores the medieval history of Lincoln, visiting the cathedral that was once the world's tallest building

A look at Le Louvre, the world's largest art museum, located in Paris, and the home of Leonardo da Vinci's celebrated portrait, the Mona Lisa

A look at the fate of Josslyn Hay, the controversial 22nd Earl of Erroll and staunch supporter of Hitler and fascism.

Testimony from witnesses, survivors and Nazis themselves reveals the truth about the mass executions carried out by the Third Reich's Einsatzgruppen

Experts question whether extraterrestrials could have helped humans build ancient structures, and if standing stones in Carnac, France, were a GPS system for ancient spacecraft

The suggestion that some animals may have been planted on Earth by aliens as part of an experiment to shape life on Earth

Helen Skelton and Alex Langlands join a dig at Elsyng Palace, one of nearly 60 royal residences owned by Henry Vlll and one of his favourite homes during his last decade

The smallest ships of war, such as the tiny canoes of the Cockleshell Heroes who led an audacious attack on German ships, and the boats that rescused soldiers from Dunkirk

A look at the tactics employed to pass strategically important ships under the nose of the enemy, and the use of intelligence to carry out naval attacks

The conspiracy theories surrounding a UFO sighting in Mexico in 1974. It was reported the object was lost over Coyame, but shortly afterwards a civilian plane crashed nearby