Luna Park in Heliopolis is one of Cairo's oldest amusement parks, operating since the early 20th century (it was part of Empain's original Heliopolis entertainment vision). The rides are modest by modern standards — a Ferris wheel, bumper cars, and a collection of traditional fairground attractions — but the park draws a genuine cross-section of Cairo families and has a charming, somewhat faded atmosphere that reflects its long history.
For visitors with children, Luna Park is an interesting alternative to the tourist circuit: genuinely used by Egyptian families, cheap, and a good place to observe ordinary Cairo social life. It's best visited in the evening and on weekends when it's fully operational. The surrounding Heliopolis streets have several good restaurants and juice bars for dinner afterwards.