The cathedral of Sant'Andrea sits on the river at the northern end of the old town, rebuilt in the nineteenth century on the site of an earlier medieval church. The current building is a fairly plain neoclassical hall church with a single nave and side chapels. The art inside is unspectacular but coherent — eighteenth-century altarpieces and a wooden choir of moderate interest.
The cathedral matters mainly because of its setting. Together with the Campanile, the river and the old mills opposite, it forms the most famous view in Portogruaro. The piazza in front is small and gives onto a balustrade above the river — the best place in town to stand for ten minutes and watch the water.