Arches　are　widely　used　when　large　spans　are　necessary,　e.g.　to　overpass　large　rivers,　and　further　possess　unquestioned　aesthetics　advantages.　Their　structural　efficiency　depends　primarily　on　optimal　material　exploitation,　i.e.　minimization　of　internal　stress　eccentricity,　and　on　minimization　of　structural　material　volume.　An　efficient　structure,　under　these　terms,　further　requires　simpler　and　lighter　scaffolding,　contributing　in　minimizing　construction　costs.　Although　arches　have　millenary　use　and　many　researches　dealing　with　this　typology　are　available　in　literature,　there　is　still　scope　for　design　optimization.　The　proposed　study　is　framed　within　this　context.　Investigation　is　limited　to　statically　determinate　plane　arches　under　vertical　load.　The　problem　of　finding　the　profile　of　an　equal　strength　catenary　subjected　to　its　self-weight　is　spread　out　to　the　case　of　an　inverted　catenary　of　equal　strength　under　its　self-weight　and　an　external　constant　load.　In　the　first　optimization　step,　constant　normal　stress　is　imposed　at　all　sections,　to　maximize　material　exploitation,　and　the　resulting　arch　centerline　shape　is　computed　in　closed　form.　In　the　second　step,　the　ensemble　of　foundations　and　arch　is　considered　and　optimized,　taking　the　linear　combination　of　arch　weight　and　thrust　as　objective　function.　The　linear　combination　is　dependent　on　a　single　variable,　and　minima　of　the　objective　function　(i.e.　optimal　geometric　shape　parameters)　are　computed　and　charted　to　be　simply　used　in　the　design　process.　©　2018