Baldassarre Longhena was a Venetian architect during the 17th century. He worked mainly in his home city of Venice where he was born in 1598. He was one of the greatest exponents of Baroque architecture in Venice at the time.

He studied under the architect Vincenzo Scamozzi and after Scamozzi's death completed his monumental Procuratie Nuove in St. Mark's Square. This huge complex of imposing residences and offices for officials of the Venetian Republic gave the square the appearance that is seen today.

His best known work is the Basilica di Santa Maria della Salute begun in 1631 to give thanks for the cessation of a plague in Venice. This two domed church on the peninsular between the Grand Canal and the Zattere is is one of the city's best known landmarks. The main entrance resembling a Roman triumphal arch, was later copied on successive churches and cathedrals not only in Venice but around the world.

He designed many other churches in the city among them the Chiesa dell'Ospedaletto and Santa Maria degli Scalzi built between 1656 and 1680 although the facade of this church was designed by Giuseppe Sardi .

One of his largest designs was the cathedral at Chioggia executed between 1624 and 1647, on the completion of the cathedral he was asked to design the palazzo, that was was later to be called Ca' Rezzonico, on the Grand Canal in Venice although he died before its completion. It was finally finished according to his designs over 100 years later.

Baldassarre Longhena died in Venice in 1682