1791, originally "habitually falling down" and used first of horses, from tumble (v.) + down (adv.); in reference to buildings, "in a dilapidated condition," from 1818.
Entries linking to tumble-down
tumble v.
c. 1300, "to perform as an acrobat," also "to fall down," perhaps from a frequentative form of Old English tumbian "dance about, tumble, leap." This is of unknown origin but apparently related to Middle Low German tummelen "to turn, dance," Dutch tuimelen "to tumble," Old High German tumon, German taumeln "to turn, reel." Transitive sense from late 14c. Related: Tumbled; tumbling.
down adv.
"in a descending direction, from a higher to a lower place, degree, or condition," late Old English shortened form of Old English ofdune "downwards," originally of dune "off from (the) hill," from dune "from the hill," dative of dun "hill" (see down (n.2)). The "hill" word is general in Germanic, but this sense development is peculiar to English. As a preposition, "in a descending direction upon or along," from late 14c.
To be down on "express disapproval of" is by 1851. Down home is from 1828 as "in one's home region," as an adjective phrase meaning "unpretentious" by 1931, American English. Down the hatch as a toast is from 1931. Down to the wire is 1901, from horse-racing.
Down Under "Australia and New Zealand" attested from 1886; Down East "Maine" is from 1825; Down South "in the Southern states of the U.S." is attested by 1834. Down the road "in the future" is by 1964, U.S. colloquial. Down-to-earth "everyday, ordinary, realistic" is by 1932.