Vintage stained glass discovered at Greenpoint therapy office

This therapist unlocked a piece of history.

Construction crews working on a refreshed storefront for a Brooklyn psychotherapy office discovered stunning, century-old stained glass that offers a sneak peek into Greenpoint’s past.

“I was totally blown away. It’s a huge unexpected gift,” Karen G. Costa, who has rented Brooklyn Psychotherapy’s office at 705 Manhattan Ave. for years, told The Post.

“I almost cried.”

The incredible find was made last month after Costa hired construction crews to revamp what she called the “ugly” Greenpoint storefront that made her therapy office look more like a jail cell.

She had hoped they would replace the corrugated metal and gates with wood paneling akin to a retro, but traditional therapy office — and was repaid with an even more vintage result.