Heidelberg is a borough located southwest of Pittsburgh in Allegheny County, Pennsylvania, United States.

[4] The borough was named after Heidelberg in Germany, the native home of a large share of the early settlers.

[6] According to the United States Census Bureau, the borough has a total area of 0.3 square miles (0.78 km2), all land.

As of the 2000 census,[13] there were 1,225 people, 571 households, and 331 families residing in the borough.

35.6% of all households were made up of individuals, and 16.8% had someone living alone who was 65 years of age or older.