Installed on the existing wayside cross in the so-called Largo do Cruzeiro, at the junction of Estrada da Sra. Da Cabeça with Rua do Cruzeiro, in other times it had an important use for passersby, indicating time by the shadow it projected. It is an artistic work, with significant historical weight, combining two important branches of knowledge: astronomy and mathematics.

Local inhabitants still continue to refer to it as a determining indicator for fulfilling the schedules of irrigation water use from the Grova irrigation.