Here is a question about this article: Philadelphia has dedicated landmarks to its sister cities. Dedicated in June 1976, the Sister Cities Plaza, a site of 0.5 acres (2,000 m2) located at 18th and Benjamin Franklin Parkway, honors Philadelphia's relationships with Tel Aviv and Florence which were its first sister cities. Another landmark, the Toruń Triangle, honoring the sister city relationship with Toruń, Poland, was constructed in 1976, west of the United Way building at 18th Street and the Benjamin Franklin Parkway. In addition, the Triangle contains the Copernicus monument. Renovations were made to Sister Cities Park in mid-2011 and on May 10, 2012, SCP was reopened and currently features an interactive fountain honoring Philadelphia's ten sister and friendship cities, a café and visitor's center, children's play area, outdoor garden, and boat pond, as well as pavilion built to environmentally friendly standards.
What is the answer to this question: How many sister cities does Philadelphia have?
ten