On a heavily trafficked street where few tourists pass in the heart of ancient Rome lies the entrance to one of the Eternal City's most extraordinary and overlooked monuments -- Trajan's Market.
Built in the second century AD as a series of vaulted offices for managers of the nearby Trajan Forum headed up by a "procurator", the architectural complex has served as a fortress, a convent and a barracks over the centuries.
Clinging to a hillside that overlooks the Roman Forum, the nearly 2,000-year-old monument offers spectacular views over the Colosseum.
The site is often referred to as the "world's oldest shopping mall," but its name is something of a misnomer as it was never the main market of Imperial Rome, site director Lucrezia Ungaro told AFP.
"It was like a large administrative centre to manage Trajan's Forum situated right by it. You have to imagine offices, meetings rooms buzzing with civil servants," he said.
The monument spreads out over thousands of square metres (feet) and is divided into six floors with dozens of arches.
Three pedestrian roads run through them, including the ancient Via Biberatica, paved with hefty basalt blocks.
The Emperor Trajan ruled between 53 and 117 AD and is well known for his extensive public building, as well as conquests that widened the empire.
Trajan's Column next to the Market commemorates his victory in the Dacian Wars when Rome took over a vast area between the Black Sea and the Adriatic.
The majestic Great Hall has the most spectacular views but weary tourists can also find a spot of calm in the Garden of the Militias, a haven in Rome's busy traffic overlooked by the mediaeval Tower of the Militias.
The red-brick tower -- the highest in Rome -- was built between the 12th and 13th centuries by noble families that turned the site into a fortress.
In the 16th century, the area was again taken over by a group of Dominican nuns who turned it into a convent that lasted for three centuries.
Following the unification of Italy and the expropriation of many Catholic Church buildings in the 19th century, it was turned into a military barracks.
Archaeological excavations in the 20th century returned the monument to a semblance of its original state by removing additions made over the centuries.
The Grand Hall is now open to the public and hosts temporary exhibitions as well as cultural events and concerts but it is still struggling to attract visitors.
"The average duration of a holiday in Rome is three days, and tourists tend to concentrate on the most famous monuments," Ungaro said, adding: "Whether to visit a monument is also a financial choice."
The entry fee for Trajan's Market is 11 euros ($14), while a 12-euro ticket covers the Colosseum, the Roman Forum and the Palatine Hill.
There are long-mooted plans to give Trajan's Market greater visibility by, for example, opening up an entrance directly from the Roman Forum below the monument -- an area that attracts thousands of tourists every day.
But getting hold of financing in the current climate is a struggle as state culture budgets have been slashed in the face of to the debt crisis.
It seems that at least for now Trajan's Market will remain a place where discerning visitors can soak in centuries of history in a haven of calm.