When fiery Roman Emperor Justinian ordered the rebuilding of the great church of Hagia Sophia in Istanbul, he was bidding for nothing less than eternal glory, both for God and for himself. Exactly how the Romans conjured up the vast golden dome floating high above the ground has astounded architects for centuries, and modern science has only recently revealed the secret that allowed this colossal structure to survive almost 1500 years of turbulent history and earthquakes. We peel back the layers of this ancient megastructure to reveal its incredible engineering secrets, and vividly bring to life the astonishing story of its construction.

To celebrate his god-like status as 'Sun of the Sun God', the creator of the Inca Empire, Pachacuti the Conqueror (his name means 'World-Shaker'), orders the building of an 'impossible' city in the sky - a sacred residence where he will commune with his fellow gods - the sun, moon, thunder, and mountains. The site, high in the Andes, perched almost two-and-a-half kilometers above sea level, on a narrow ridge of volcanic granite, faces the Emperor's engineers with an almost impossible task. How to make sure the city, where they will erect spectacular temples, altars, residences, and fountains - all built on shifting fractured rock - will resist the torrential rains, landslides, and earth tremors of the region. Brilliantly conceived, perfectly executed, using techniques that even surpass those of today - and mystify architects, engineers, and archeologists - the Inca create their masterpiece: Machu Picchu. When Spanish Conquistadores and European smallpox destroy the Inca Empire, Machu Picchu is abandoned, lost, and forgotten - living on only in legend. Rediscovered, covered in jungle, only 100 years ago, Machu Picchu remains today, just as the Emperor Pachacuti intended, one the most spectacular - awe-inspiring and mysterious - monuments in the world.

Stuck between a rock and a hard place in the unforgiving deserts of Petra, in modern day Jordan, the Nabataean dream of a glorious royal city must have seemed like little more than a very grand mirage. Standing at the crossroads of the ancient Near East, discover how these wealthy traders would turn engineering on its head to create one of the most awe-inspiring monuments, the Khazneh. Discover how the Nabataeans held back flash-floods to protect their greatest monument, and why clues hidden deep in the building reveal the great king whose vision created this masterpiece. We travel back through time to reveal how human resourcefulness and courageous endeavour would create one of the ancient world's most magnificent megastructures, the Khazneh.

The Alhambra is the greatest example of Islamic military architecture in Europe. In 1238, the Moorish Sultan Muhammad I withdrew to Granada, in southern Spain, to create a bastion that would protect his family against Christian attack. It was here, against the backdrop of war and terror that Muhammad began a construction process that would span more than one and a half centuries and create one of the most beautiful palaces in the world. But just how did he construct such an impregnable fortress? How did he raise water from the river 100 meters below, to irrigate its gardens? And why is Greek geometry a crucial part of this Muslim masterpiece? Alhambra will bring to life the ingenious engineering solutions and treacherous political betrayals that gave birth to what is arguably the most perfect example of Moorish architecture in existence.

England 1666. A great fire engulfs the city of London, devastating everything in its path, including the magnificent Gothic cathedral of Old St Paul's. Christopher Wren's dream is to raise a new cathedral from the ashes, the centre piece of a city set to rival the grandeur of Ancient Rome. With a mathematician's belief in the inherent superiority of Classical architecture, Wren wants to create England's first Baroque cathedral, crowned by a great dome. But even before the first stone is laid, he faces unprecedented challenges. Through a mixture of defiance, cunning and engineering brilliance, Wren sets out to realise his vision. And 36 years later, the Phoenix of St Paul's rises from the ashes of the Great Fire to become an iconic landmark of London.

Hidden deep in the impenetrable jungle of Cambodia, the mighty temple of Angkor Wat is a humbling representation of the Hindu universe. A usurper king who seizes the throne by murdering his great uncle, King Suryavarman II seeks to justify his absolute power over the enormous Khmer Empire with a towering monument to Hindu god Vishnu. Angkor Wat will also serve as the new king's personal mausoleum, and be his personal heaven for the afterlife. Suryavarman's vision is one of staggering ambition. The largest of the five huge towers soars 65m into the sky, surrounded by a network of concentric courtyards, causeways and outbuildings, all guarded by an enormous 200 m wide moat. Experts estimate workers must cut and transport at least 300 blocks of sandstone weighing from three to fifteen tonnes every day to ensure the temple is completed in Suryavarman's lifetime. Completed in a staggering thirty-five years, Angkor Wat, remains one of the largest and awe-inspiring religious monuments ever built.