You are now standing in front of what many consider the greatest surviving achievement of ancient Greek art - and one of the most extraordinary objects in this museum.
The Parthenon was built around 450 BC as a temple dedicated to the goddess Athena, patron of Athens. Its great size and lavish use of white marble was intended to show off the city's power and wealth at the height of its empire, under the statesman Pericles.
It was also built for a very specific reason. Indeed in 480 BC, the Persian Empire had attacked Athens and destroyed the Acropolis. The Parthenon was Pericles's answer - built 33 years later as a defiant statement of everything Athens had become.
Pericles himself claimed that Athens was the school of Hellas - the school of Greece. The Acropolis was a symbol of this effort to promote Athens as the greatest of all Greek cities.
The sculptures were made under the supervision of the sculptor Pheidias, working alongside architects Ictinus and Callicrates.
The statues are organised into 3 layers, each telling a different story.
First, the carved panels running high above the columns - the metopes - depict mythological battles: gods against giants, Greeks against Trojans, Lapiths against centaurs. Allegories of civilisation triumphing over chaos, order over barbarism, Athens over Persia.
Then the frieze, running continuously around the interior of the temple, shows the Panathenaic procession - a great festival held every 4 years to celebrate the birthday of Athena.
The culmination of the festival was the redraping of the great statue of Athena inside the temple in a new cloak, woven by the citizens of Athens.
What makes this extraordinary is that the frieze doesn't depict gods or heroes or myths - rather it depicts the people of Athens themselves. This is almost without precedent in ancient Greek art.
Finally, the pediments - the large triangular spaces formed where the two slopes of the roof meet - show the birth of Athena from the head of Zeus on one side, and the contest between Athena and Poseidon for dominion over Athens on the other.
Fun fact : although the marbles look white today, they were at the time much more colorful. Indeed recent scientific analysis has found traces of Egyptian blue, purple and white - showing that the sculptures were once brightly coloured. The originals were vivid, painted, alive with colour.
The British Museum holds 75 metres of the original frieze, 15 metopes and 17 pedimental figures. The other half of the surviving sculptures are in the Acropolis Museum in Athens. Greece has been formally requesting their reunification since 1983. It is the most contested ownership dispute in the museum world.
