Alongside the apse of the cathedral, standing 89.32 metres tall, is the Ghirlandina belltower, the symbol of the city of Modena. The Ghirlandina was given this nickname by the city's inhabitants due to the double ring of parapets that crown its steeple, "as light as garlands", ghirlanda in Italian.

Built as the belltower for the cathedral, this tower has however played an important civic function since its origins: the ringing of its bells marked the time for life in the city, it announced the opening of the gates in the city walls and acting as a warning for the people in situations of alarm and danger. Its mighty walls guarded the so-called “Sacristy" of the Municipality, which was home to the strongboxes, public documents and objects of great symbolic value like the famous fourteenth-century “Secchia rapita” or Stolen Bucket (a copy is currently on display). This humble yet supreme object of contention between the people of Modena and Bologna in the enflamed historic battle of Zappolino (1325) was raised to fame in the mock-heroic poem of the same name by Alessandro Tassoni.

Debate regarding the chronology of the Ghirlandina is still open because direct historic sources are missing for the initial building stages. By about 1160 the foundations were being dug and the tower was built to a height of 11 metres. Between 1167 and 1184, after a brief pause due to settlement of the site, building reached the fifth floor, topped by four corner turrets. In 1260 the sixth storey was built, which incorporated the turrets. In 1319, the tower was completed with the octagonal pinnacle, exquisitely gothic and originally decorated by numerous spires, to plans by Enrico da Campione. 

The outside of the Ghirlandina is characterised by a rich array of sculptures and by stone cladding, the material salvaged from the Roman Mutina, as revealed by scientific investigations carried out during the recent renovation work, started in 2007 and completed in 2011.

Inside the Ghirlandina, on the fifth floor there is the so-called Stanza dei Torresani, once lived in by the tower custodians and where important capitals can be admired.

Together with the cathedral and Piazza Grande, the Ghirlandina belltower has been a UNESCO World Heritage Site since 1997.