The discovery of seven graves in the basement of a home undergoing renovation in the city's Fairmount section is a reminder that Philadelphia is dotted with forgotten burial grounds.

The origins of the bones - found in the graves on the 800 block of North 20th Street - has not been determined. But records show that one of the city's many potter's fields was located nearby, at North 19th Street and Fairmount Avenue.

The burial ground served as a last resting place for many of those who died at Bush Hill, a former estate that was first used as a hospital during the 1793 yellow-fever outbreak and then became the site of the city's Municipal Hospital for Contagious Diseases until 1855.

Until the mid-1980s, Philadelphia buried the remains of its unknown, unclaimed or indigent dead in various city burial grounds.

Many, of course, have heard that Washington Square was the first official public burial ground, and that Revolutionary War soldiers and victims of the yellow-fever epidemic were interred there.

After it closed in 1794, public burial grounds came to dot the city's landscape, including the Fairmount site.

The city's last potter's field opened in 1956 at Dunks Ferry and Mechanicsville Roads in the Far Northeast and accepted the dead for three decades. One of the first graves was for a still unidentified murder victim known as the "Boy in the Box."

Before that, the city's potter's field was in a triangular plot now used as a police parking lot at Luzerne Street and Whitaker Avenue in North Philadelphia.

When it opened in 1914, the burial ground adjoined Philadelphia Municipal Hospital. It became the final destination for thousands who died in the 1918 flu epidemic or who died destitute during the Depression.

In those days, the dead were buried for a year and a day before their remains were cremated at a crematorium on the hospital grounds.

But after the crematorium broke in the 1940s, the bodies piled up at the potter's field, and the conditions became something of a scandal in the 1955 mayoral race, though Republican W. Thacher Longstreth could not leverage the outrage to defeat Democrat Richardson Dilworth.

These days, Philadelphia's "potter's field" can be found in a room off the morgue at the city Medical Examiner's Office on University Avenue.

Stored there are the ashes of about 2,400 individuals, almost all of them identified but unclaimed.

Here are locations of some other potter's fields based on "A Register of the Burial Grounds of Philadelphia," a handwritten manuscript compiled by Charles R. Barker in 1944 and on file at the City Archives.

-- Foot of Race Street at the Schuylkill.

-- Logan Square.

-- South side of Lombard Street between Ninth and 12th Streets.

-- Northwest corner of 15th and Catharine Streets.

-- South side of Carpenter Street between 11th and 12th Streets.

-- George and Ginnodo Streets in Francisville.

-- Playground at West Queen Lane and Pulaski Avenue in Germantown.

-- Franklin Field.

-- Reyburn Park in North Philadelphia