BOSTON — Children splashed in a shallow pool in Boston Common as a guide in a tricorner hat led a tour last week, pointing out Revolutionary War sites. Yet here, in the nation’s oldest park, some people worry that this city is closing in around its open spaces, with skyscrapers blanketing its parks in shadow.

“It’s going to be hidden, buried within the buildings,” Sonuschka Pierre-Mike, 38, said of the beloved Common, as she strolled through it the other day.

Boston is riding the crest of what city officials say is the biggest building boom in its history, with cranes lifting glassy towers into place and raising the city’s unassuming profile.

The surge of construction is also plunging some of its most cherished sites into deepening shadow, testing state laws that have long balanced economic development with protection of sunlight and open space.