A basement or cellar was an underground room in a building.
Vicki, after leaving the First Doctor to live in ancient Troy with Troilus, kept a Phoenix cinder in a burning oil lamp in the basement of a temple. She discovered over time that it was sentient and telepathic. Vicki often visited the creature, as she felt that they were both alone and needed someone to talk to. (AUDIO: Frostfire)
Lupton opened a connection to Metebelis III in the basement of a Buddhist meditation centre. This enabled the Eight Legs to come to Earth to get the blue crystal from the Third Doctor. (TV: Planet of the Spiders)
The Fourth Doctor, Romana and Duggan find the other Mona Lisas in Count Scarlioni's cellar. TV: City of Death
The 16th century fragment of Scaroth, Captain Tancredi, had Leonardo da Vinci paint six extra copies of the Mona Lisa. He then had them sealed in a secret cellar room in a house in Paris so they would be available to his 20th century fragment. (TV: City of Death)
On 17th century Earth, a stranded group of escaped Terileptil prisoners hid in the cellar of a manor house. (TV: The Visitation)
Shockeye eating a rat in the basement of the Doña Arana's hacienda. TV: The Two Doctors
Chessene, Shockeye and Major Varl seized a Spanish hacienda and killed its owner, Doña Arana. This allowed Dastari to set up his operating theatre from Space Station Camera in the basement of the hacienda undisturbed. (TV: The Two Doctors)
After Matheson Catcher found the Seventh Doctor's amaranth, it turned his cellar into an unTARDIS. (PROSE: Christmas on a Rational Planet)
Haygoth kept a body-print machine with the human Trevor inside it in Patricia Ryder's cellar. (AUDIO: The Zygon Who Fell to Earth)
The Ninth Doctor first met Rose Tyler in the basement of Henrik's, where he saved her from a group of Autons which had been made to look like shop window mannequins. (TV: Rose)
The Weeping Angels forever frozen in the basement of Wester Drumlins. (TV: Blink)
When the TARDIS landed in the basement of Wester Drumlins, some Weeping Angels transported the Tenth Doctor and Martha Jones to 1969. They then tried to get into the TARDIS to feed on its time energy, but Sally Sparrow took the TARDIS key from them whilst they were quantum locked. (TV: Blink)
After a Weeping Angel sent Rory Williams back in time to 1938, Julius Grayle had him locked in his basement with a group of baby Weeping Angels. Instead of transporting him through time again, though, they moved him physically to Winter Quay. (TV: The Angels Take Manhattan)
Following his regeneration, the Twelfth Doctor encountered a group of 51st century robots that had crashed in a timeship in Earth's past millions of years before. They had been harvesting body parts to repair themselves. By the 19th century, they were using the basement of a restaurant beneath which their ship was buried to carry out their activities. (TV: Deep Breath)
Ianto Jones kept his partially Cyber-converted girlfriend Lisa Hallett in the Torchwood Three basement whilst he tried to figure out how to make her human again. (TV: Cyberwoman)
The International Gallery of London took possession of a collection of Giuseppe di Cattivo's works in Victorian times, including his painting The Abomination. They stored it in their basement vaults until the early 21st century, when it came to life and was then destroyed by K9. (TV: Mona Lisa's Revenge)
Irving Braxiatel said that his father had a cellar full of Draconian brandy. (AUDIO: Everybody Loves Irving)
On Espero, Princess Sensimi kept a night beast in the cellar of the palace. (PROSE: Halflife)
After the Spy Master killed everyone on Gallifrey, he planned to put a torture room in the cellar of The Citadel. (TV: The Timeless Children)