MONTREAL -- The City of Montreal is hoping that an upcoming archeological dig will unearth some old secrets, including artifacts from a former convent and 18th century prison whose ruins lie under city hall.

The elegant limestone building that currently houses city hall sits on a site that was once home to a Jesuit convent, which was seized by the Crown after the 1763 conquest of New France and transformed into a jail around 1768.

Earlier this week the City of Montreal put out a call for bidders for archeological services at Place Vauquelin, the square in front of city hall.

In an email, city spokeswoman Valerie De Gagne said that beginning this fall archeologists will explore the soil for traces of the convent, which dates back to 1692 and included a chapel, church, residence, yard and garden. They will also sift the ruins of a later jail, built in 1808 after the converted convent buildings were damaged by fire.

The work has been commissioned ahead of planned repairs to the square and the foundations of city hall and the adjoining building, which houses the city's finance department.

"The archeologists will survey the archeological traces that remain, and will sift the soil where they are found," De Gagne wrote. "This will allow them to learn more about the activities that took place in this location over time."

Even the "newer" jail constructed in 1808 did not serve as a jail for long, as Montreal's exploding population meant that it was outgrown by 1811.

It was used as an army barracks for several years beginning beginning in 1837, until it was demolished to make way for the building of the former Montreal courthouse in 1850.

Dinu Bumbaru of Heritage Montreal says a successful dig could allow searchers to precisely locate the convent buildings, and provide hints as to the nature of daily life and activities -- details such as the size of the garden, and what was grown there.

Excavating the two jails, he said, could teach historians more about prison life.

Records would suggest that punishments for 18th and 19th century offenders was harsh.

In his 1886 book "History of the Montreal prison from A.D. 1784 to A.D. 1886," John Douglas Borthwick wrote of the liberal use of the whipping post as a form of punishment, and lamented its fall from favour due to what he saw as the "mawkish sentimentality" and overly soft treatment of prisoners in the later 19th century.

He recounted that prisoners were also placed on a pillory for public shaming. Hangings, he wrote, were carried out within days of a sentence.

"Some of the most flagrant violations of both civil and moral law were then almost unknown, and it would significantly reduce the number of crimes were now-adays whipping in several instances to be enforced," wrote the 19th century historian.

De Gagne says it remains too early to guess what the archeologists might find, or to speculate whether any of the ruins may be open to the public.

Bidding on the contract is open until mid-August, and De Gagne said work is expected to take place this fall and in the spring of 2016.