The Thomas Leiper Estate, also known as Avondale, is an historic, American estate that is located in Wallingford in Nether Providence Township, Delaware County, Pennsylvania.

It was added to the National Register of Historic Places in 1971.

[1] Built by Thomas Leiper circa 1785, this historic estate was named Strath Haven after Leiper's birthplace in Strathaven, Scotland, and includes a three-story, yellow-stuccoed mansion house, a "Fireproof" vault, a communal outhouse, a barn, a carriage house, a smokehouse, a warehouse, a tenant's house, and a quarry.

It was added to the National Register of Historic Places in 1971.

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