This traditional green project prevented leaks, contained rust and added to the attractiveness of the home.  When I emailed this Washington DC owner that her restored roof is hidden from view by overgrown tree limbs,  she emailed back,

“The weeping trees are babies of one of the original Japanese cherry trees that were sent in 1912.  The owner of the house back then was a landscape architect, and he worked at the Dept. of Agriculture.  I don’t know how he came into possession of the tree……”