The　new　Fourth　bridge　over　the　Grand　Canal,　designed　by　the　Spanish　architect　Santiago　Calatrava;　which　was　recently　completed　in　Venice,　is　characterized　by　some　original　solutions　in　the　Venetian　panorama　of　traditional　bridge　design.　Its　stunning　elevation,　on　a　single　80　m　span　depressed　＂Vierendeel＂　arch　with　a　span/rise　ratio　of　1/16,　implies　an　extraordinary　challenge　for　the　foundation　system　in　the　muddy　Venetian　soil.　The　cross　section　of　the　bridge　presents　an　open　star-shaped　layout　with　a　central　triangular　steel　box　girder,　thus　implying　a　remarkable　torsional　deformability.　The　loose　mechanical　properties　of　the　Venetian　soil,　together　with　the　peculiar　intrinsic　structural　and　geometric　characteristics　of　the　footbridge,　imposed　a　careful　revision　of　the　original　design　and　some　modifications　aimed　at　achieving　a　globally　stiffer　structure　without　any　alteration　to　its　external　outfit.　The　footbridge　was　pre-assembled　and　loaded　prior　to　erection　trying　to　simulate　its　final　condition　in　terms　of　external　restraints.　In　this　phase　a　monitoring　instrumentation　was　installed　in　order　to　better　investigate　its　response.　The　erection　design　was　conceived　in　order　to　take　into　account　the　extremely　bounding　conditions　of　the　project　area.　A　set　of　full-scale　static　tests　of　the　structure　was　carried　out　before　and　after　the　erection　to　check　the　behaviour　of　the　bridge.