Feat of engineering

Not this year's nest, at least one or two years old. How fab, mud, spit and a bit of stuff, lasts years (sadly we had them all taken down 3 years ago to paint under the eaves) but it is said the housemartin family can return for 50 years and more to the same spot...every year we get more nests, so our house is now home to more than just 'us indoors', how sweet.