Bridgetown
Bridgetown was a settlement on Quinnis once visited by the First Doctor and Susan. It consisted of an array of criss-crossing layers of bridges and viaducts. As rain on Quinnis fell in amounts large enough to cause a flood, Bridgetown was built like a huge gutter, allowing the excess water to be swept away.
When the Doctor and Susan arrived, they came at a time when the great rain was years overdue, the Doctor being drafted into the role of rainmaker. Unable to escape back to his TARDIS, the Doctor conspired to bring about the rain via atmospheric excitation only for the rain to naturally fall. When it came, Susan befriended Meedla, unaware that she was the Shrazer of legend. Seeking to escape Quinnis, Meedla stole Susan's TARDIS key when the floods came as Susan sought refuge with Amlanti.
The next morning, as the water brought hostile vegetation beneath Bridgetown to life, the town began a manhunt for Meedla while a resolute Doctor descended into the foliage to retrieve his TARDIS, swept away by the floods. Though the Doctor reached his ship, he was unable to enter before the plants surrounded the craft. A desperate Susan bargained with Meedla to rescue the Doctor in exchange for passage off-world only for the Doctor to be rescued by ornithopter. When the plants began reaching Bridgetown, the Doctor used his knowledge of chemistry to kill them before Avelier Parch IV killed Meedla. After Susan had reclaimed her TARDIS key, the two Time Lords left the town, the Doctor stating that his granddaughter needed structure in her life. (AUDIO: Quinnis)