At the far north of Cannaregio, where Fondamenta Gaspare Contarini runs along the rio della Madonna dell’Orto and Venice begins to blur into the lagoon, opens this rich 17th-century facade. The palazzo — which the Venetians know by a double surname, Minelli-Spada — is in good company: attached to the great Palazzo Contarini dal Zaffo, opposite, beyond the rio, the Palazzo Mastelli known as del Cammello.