In 1880, Armstrong presented the landscaped park of Jesmond Dene as a gift for the benefit of the inhabitants of Newcastle, with an additional gift of land in 1883.
The park, known initially as Armstrong Park, was officially opened by the Prince and Princess of Wales during their visit to Newcastle in 1884. A special volume was published to commemorate the royal visit, carrying a striking coloured plan of the park and bearing a dedication to Armstrong in gratitude for his "princely gifts" to the town's inhabitants.