In a neighborhood off Hesperian Boulevard in Hayward, in a one-story stucco house with a peach tree out front, Roy and Linda Tran built a small skate park in their driveway in 2003. They poured the concrete themselves. They did not get a permit. The city has never said anything.

It started, Roy says, because their son Daniel asked. He was 12. He wanted a quarter-pipe. Roy worked at a building supply company and could get materials. Linda thought it would last a year, until Daniel got bored.

Daniel is 35 now and lives in Portland. The driveway is still a skate park. On a recent Wednesday afternoon, eight kids between the ages of 9 and 16 were rotating through it, four boards in motion at any given time, the rest waiting their turn on a milk crate.

“They show up,” Linda says. “They’ve always shown up. We don’t advertise. Their cousins or their friends bring them. Some of these kids, I’ve been watching grow up since they were eight.”

Linda makes lemonade in summer and hot chocolate in winter and puts a folding table by the garage with paper cups. The rule, she says, is that kids can stay as long as they want as long as they put their cups in the recycling and don’t scream. Nobody has ever broken the second rule.

A boy named Marcus, 14, has been coming since he was 11. His older brother used to come. Now Marcus brings his younger sister. He tells me, without prompting, that he has fallen on the concrete fourteen times and only cried once.

“Mr. Tran taught me how to fall,” Marcus says. “He told me, you don’t catch yourself with your wrist. You roll into your shoulder. Like you’re hugging the ground.”

Roy is 67 and retired now. He still mixes a fresh batch of concrete every two summers to patch the rough spots. Linda still puts out the lemonade. Their peach tree is still there.