A North End privy sealed for more than a century has yielded thousands of artifacts that are giving archeologists an unprecedented look at how the world’s oldest profession was practiced by improper Bostonians of the 19th century.

From toothbrushes to jewelry to cosmetics, and parts of 19 syringes used for hygiene, the treasure trove plucked from a now-buried site near Haymarket is evidence of a thriving, racy economy that the city’s prim Victorian image never acknowledges.

But the 3,000 items found during a 1993 archeological survey linked to the Big Dig, behind long-vanished rowhouses on Endicott Street, show the trappings of a busy brothel aimed at middle-class customers.

The findings, the most of their kind ever discovered in Boston, have not been previously publicized outside academic and archeological circles. Limits in funding and staff have consigned most of them to private storage and occasional analysis by students and researchers.

That work has been a colorful revelation, Beaudry and other archeologists said. Research into housing records has shown that the property at 27 and 29 Endicott St. probably was used as a brothel for much of the time between 1852 and 1883.

In a city where 5,000 prostitutes are estimated to have worked in the last half of the 19th century, the property had plenty of company. Beaudry estimated that the North End, Boston’s red-light district of the time, contained 30 to 40 brothels within its tight, congested confines....