The port city on the gulf of the same name was a part of Austria from the Middle Ages until the end of WW I. For centuries it was one of Europe's leading economic and cultural centers, its location on the Adriatic Sea making it one of the few ports in the Austro-Hungarian Empire. The city's fortunes declined after the region was annexed by Italy in 1918, however, and today Trieste leads a somewhat subdued existence as a remote enclave on a strip of coastline squeezed in between Slovenia and the sea. The port's unique location is reflected in its culture and architecture, which reveal an eclectic mix of Austrian and Venetian elements. A good example of this are the neoclassical facades of the buildings lining the Piazza dell'Unità, the main square along the seafront. Yet the city's history goes back much farther than the Austrian Empire, as evidenced by the Arco di Riccardo, a Roman gate, and the Roman amphitheater dating from the 1st century AD.