It opens onto a small public square on its west side, distinguished by the trees at its center, which was historically designated as the Souq el-Henna or henna market.

[6]: 73  The institution may have influenced the foundation and function of similar establishments elsewhere in Morocco and Spain, including a hospital for the mentally ill founded in Valencia in 1410.

[6][5] In maristans across the Islamic world, mental illness was treated with music, aromas, water and other methods designed to soothe them.

[8][5] The Maristan of Sidi Frej became the most famous and important institution of its kind in Fes, and was visited by major scholars of medicine of the time such as Abu Bakr al-Korachi, an Andalusian from Malaga.

[6] As a result, for most of its later history the maristan appears to have served mainly as a hospice providing shelter and food for the city's destitute, mentally ill, and other individuals excluded from society.

[6][8] Its inauguration may have also been in part motivated by attempts to make colonial rule, coming under heavy opposition, appear more respectful of local Muslim traditions and institutions.

It also mentions that the fountain's construction was supervised by the sultan's vizier, Abu Zakariya Yahya ibn Ziyan al-Wattasi (who founded the subsequent Wattasid dynasty).

[9] The inscription and the small marble panel ornaments are from the original Marinid construction, while the wooden canopy above dates from the 17th century restoration.