53 Pa. Stat. § 16523
The councils of said city, whenever they shall select any square or other area of ground to be laid out and maintained forever as an open public place or park, for the health and enjoyment of the people, shall have the power, if they cannot agree with the owner or owners thereof as to price, to cause a petition to be filed in the court of quarter sessions of the city and county of Philadelphia, on behalf of said city, setting forth by proper metes and bounds the ground so selected, and that by ordinance the said councils have appropriated the same for said purpose; whereupon the said court shall appoint a jury to assess the damages in the manner now provided by law, and the proceedings thereupon shall be the same and with the like effect as upon the assessment of damages for the opening of streets in said city.
53 P.S. § 16523