1560s, "to bring (a building) to ruin, bring into a ruinous condition by misuse or neglect," from Latin dilapidatus, past participle of dilapidare "to squander, waste," originally "to throw stones, scatter like stones," from dis- "asunder" (see dis-) + lapidare "throw stones at," from lapis (genitive lapidis) "stone" (see lapideous). Perhaps the English word is a back-formation from dilapidation. Intransitive sense of "fall into total or partial ruin" is from 1712.

"in ruins, broken down," 1806, past-participle adjective from dilapidate.