This series of graphics and photos depicts the history of a project in Philadelphia to build the Pennsylvania Avenue subway and sewer connections, circa 1900.

View showing Philadelphia & Reading Railroad tracks and conditions on Pennsylvania Avenue.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 5.

Sketch illustrating the plan for the depression of Philadelphia & Reading Railroad tracks on Pennsylvania Avenue west of Broad St. and the abolishment of grade crossings on all intersection streets, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 7.

General plan for the depression of the tracks of the Philadelphia & Reading Railroad on Pennsylvania Avenue and Noble Street, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 9.

Plan of sewers to be reconstructed in connection with the depression of the tracks of the Philadelphia & Reading Railroad on Pennsylvania Avenue, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 11.

Main sewer on 24th Street and Pennsylvania Avenue, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 13.

Typical section of underground structures in 24th Street between Spring Garden Street and Pennsylvania Avenue, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 16.

Section of Callowhill Street Sewer showing flume used for plastering invert on curves, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 21.

General details for pipe sewers, wellhole, and manhole with flushing gate in the Pennsylvania Avenue subway project, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 25.

General details for egg-shaped sewers and manholes with in the Pennsylvania Avenue subway project, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), p. 27.

Top photo - open cut on 24th Street, north of Callowhill Street, circa 1900.

Bottom photo - tunnel on 24th Street, under Pennsylvania Avenue, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), plate I.

Top photo - tunnel on Pennsylvania Avenue west of 26th Street, circa 1900.

Bottom photo - sewer in tunnel on Callowhill Street, circa 1900.

Source: George S. Webster and Samuel Tobias Wagner, "History of the Pennsylvania Avenue Subway, Philadelphia, and Sewer Construction Connected Therewith," Transactions of the American Society of Civil Engineers, Volume XLIV (December 1900), plate II.