Weaver bird nests

Sociable weaver (Philetairus socius) nest in a quiver tree (Aloe dichotoma), Fish River Canyon, Namibia. Sociable weavers construct the largest nests of any bird, housing hundreds of individuals spanning many generations.

Very impressive!  Credit here, via Electric Orchids.

Reposted from 2011 to add this photo of weaver bird nests in India -

- and this video of a weaver bird at work:

I will never cease to amazed at how birds can do this.