At the centre of Campiello Emo stands the Well of the Frari, dug towards the end of the 1400s, with a diameter of about 3 meters, connecting a cavity full of drinking water after 6 meters of limestone.

For many years, including recent ones, this well provided drinking water to all of Gradisca, even in periods of maximum drought, by means of a suction pump that went 6 meters below the water surface, i.e. about 12 meters from the surface of the ground.

Today, in place of the historic public pump and the building that stood outside and was used as a water pumping station, the Well is embellished by the parapet of the ancient Castle well, bearing the coat of arms and an inscription in Latin recalling Baron Giovanni de Hojos, a Hungarian nobleman of Spanish origin, who was the third Captain of Gradisca from 1557 to 1560.

Recent speleological research conducted by the cave divers of the "C. Seppenhofer” reserach centre of Gorizia have confirmed the presence inside the well of specimens of olm (Proteus anguinus), testifying to the karst spur under the castle.