Two photographers taking each others' picture with hand-held cameras while perched on roof. This image is public domain. For more information on this amazing photograph, please click on this link: http://lcweb2.loc.gov/cgi-bin/query/D?ils:1:./temp/~pp_WtBE::@@@mdb=fsaall,brum,detr,swann,look,gottscho,pan,horyd,genthe,var,cai,cd,hh,yan,lomax,ils,prok,brhc,nclc,matpc,iucpub,tgmi,lamb,hec,krb,