San Leonardo was first built in 1025, and was linked to the foundation of Venice's first Scuola Grande, Santa Maria della Carità, which later moved to Dorsoduro and now houses the Accademia.
Meanwhile the church it left behind was rebuilt in 1794 by Bernardino Maccaruzzi and suppressed seven years later by the French (a Venetian record for brevity!), before filling various other secular functions, most recently as an exhibition space.
The church originally had a campanile, too, but it collapsed in 1595, killing ten who were underneath it.
Also see San Marcuola.
Hours Open only for special exhibitions
Campo San Leonardo
Vaporetto San Marcuola
Image by Axbay, Creative Commons License