The reconstruction of Dilworth Park began immediately after the Occupy protesters were moved out in 2011, and ever since the space reopened last fall, people have wondered how it would accommodate demonstrations. We got the answer at Thursday's "Philly Is Baltimore" rally.

Although the park sprawls across nearly three acres, hundreds of demonstrators were boxed into a small corner by the spray fountain, which covers much of its northern half. Because the jets weren't shut off until after 5:30 p.m., more than an hour after the protest started, the fountain effectively served as a form of crowd control. The participants were squeezed into the area between the cafe and the glass headhouses.

As the front door to City Hall, Dilworth Park is probably Philadelphia's most symbolic public space, the city's family room. It's the place where all Philadelphians should feel welcomed and comfortable.

When responsibility for Dilworth's management was transferred to the private Center City District, the goal was to create a flexible, multipurpose surface that could be used for all kinds of events. To that end, the landscape architecture firm Olin equipped Dilworth with a flat, inground fountain that can be turned off with a touch of a button. The park's surface has been cleared many times for movies and concerts, as well as for this winter's skating rink.

So why wasn't the fountain stopped for Thursday's rally?

Paul Levy, the head of the Center City District, said that because the demonstrators did not obtain a permit and the protest was officially "unplanned," there was no obligation to shut off the fountain.

Nevertheless, before the rally even started, Levy acknowledged, employees were instructed to move loose chairs away from the cafe area and secure them with cables.

Only after the sprays became a subject of discussion on Twitter did he order water turned off.

Because public space is the physical embodiment of free speech, design can speak volumes.

"When I noticed the fountains weren't turned off, I assumed it was intentional, a way of limiting where people could gather," said Alex Feldman, a developer who works in a building overlooking Dilworth.

That may not have been the message that Dilworth's new landscape intended to convey. But that was the one that was understood.