。
By evening the tree's shadow had reached the wall.
Literal
Evening-by that tree-of shadow [topic-は] wall [at-に] reach-[past-いた].
A quietly poetic observation. 届く ('to reach, arrive at') takes its destination with に — useful pair with 届ける ('to deliver'). The ending 届いた is the plain past of a -く verb and contrasts with the ongoing 届いている. Evocative single-shot descriptive sentences like this one are common in written Japanese and worth learning from — note how the visual detail carries the whole sentence.