Location from harry-potter-deathly-hallows by
Slytherin's hidden underground lair beneath Hogwarts -- reopened during the Battle by Ron mimicking Parseltongue, becoming the source of Basilisk fangs needed to destroy Horcruxes.
Ron Weasley opened the Chamber of Secrets during the Battle of Hogwarts by mimicking the Parseltongue sounds he'd heard Harry use. Hermione collected Basilisk fangs from the dead serpent's skull and used one to destroy Hufflepuff's Cup. The chamber -- built to house a weapon against Muggle-borns -- became the source of a weapon against Voldemort. Ron and Hermione's kiss happened here, ankle-deep in the Chamber's dark water, surrounded by the skeleton of a thousand-year-old snake. It was not romantic by any conventional measure. It was perfect.
Long subterranean hall with serpent-carved pillars, green-tinged torchlight, the massive stone face of Salazar Slytherin. Damp, dark, the dead Basilisk's skeleton still sprawled on the floor after five years.
Also known as: the Chamber of Secrets, Chamber of Secrets