expression
Used in the pattern ～に至るまで to emphasize that something extends to an extreme or unexpected point, often translated as 'even' or 'as far as'.
細部に至るまで徹底的に調査した。
We investigated thoroughly, down to the smallest detail.
彼は服装に至るまで完璧にこだわる。
He is particular about everything, even his clothing.
expression
from ... to ...; everything from ... to ...
Used in the pattern ～から～に至るまで to list a range, often implying comprehensiveness or variety.
子供から大人に至るまで、誰でも楽しめるイベントです。
It's an event that everyone can enjoy, from children to adults.
頭のてっぺんから足の先に至るまで、泥だらけだった。
I was covered in mud from head to toe.
Combination of the verb 至る (to reach, to arrive at) and the particle まで (until, as far as). The phrase literally means 'reaching as far as' and is used to emphasize extent or range.