At the mouth of the Cannaregio Canal, beside the church of San Geremia, the colossal Baroque mass of Palazzo Labia - the last of the great palaces built in Venice - is the summit of 18th-century ostentation: the house that a Catalan family of immensely rich merchants - deserving citizens for two centuries, admitted to the patriciate in 1646 with three hundred thousand ducats offered for the war of Candia - built to prove it had arrived.