Monfalcone (Italian pronunciation: [moɱfalˈkoːne]; Bisiacco: Mofalcòn; Friulian: Monfalcon; Slovene: Tržič; archaic German: Falkenberg) is a town and comune (municipality) in the Regional decentralization entity of Gorizia in Friuli-Venezia Giulia, northern Italy, located on the Gulf of Trieste. Its name means 'falcon mountain' (see Montfaucon in French and Falkenberg in Germanic languages).

It is a major industrial centre for manufacturing ships, airplanes, textiles, chemicals, and refined oil, and is home to one of Fincantieri's main shipyards. Monfalcone is the northernmost city on the Mediterranean Sea.

Monfalcone is the fifth most populous town in Friuli-Venezia Giulia and the main centre of Bisiacaria territory. Joined to its neighbourhoods, it has about 50,000 inhabitants. The town lies between the Karst hills and the Adriatic coast, and it is the northernmost port of the Mediterranean Sea.

The municipality extends along the northern coastal strip of the Adriatic Sea for 24.39 km and is enclosed to the south by the bay of Panzano and to the north-east by the Carso, while to the north-west it borders the municipalities of Ronchi dei Legionari and Staranzano. From a seismic point of view, the municipal territory is located, according to the Civil Protection classification, in zone 3 subject to low seismicity.

In prehistoric times the area of Monfalcone housed several fortified villages called castellieri. After the foundation of the Roman city of Aquileia (181 BC), some thermal buildings were created on the hills, known as Insulae Clarae.

After Ostrogoth, Byzantine, Lombard, and Frankish domination, Monfalcone was controlled by the Patriarchs of Aquileia starting from 967. The Venetians conquered it in 1420 after three days of siege, keeping it until 1511, when it fell to the French. Conquered back by Venice, it was ravaged by the troops of Habsburg Emperor Maximilian I in 1513, who destroyed the Rocca fortress. In 1521 it was returned to the Republic of Venice, under which it remained until its dissolution by the 1797 Treaty of Campo Formio.

From 1805 it was controlled by the French Empire until the fall of Napoleon in 1814, after which it was included in the Kingdom of Illyria, part of the Austrian Empire. Incorporated into the crown land of Gorizia and Gradisca, it belonged to the Austrian Littoral from 1849. The first shipyards arose from about 1908 onwards, among them the Cantiere Navale Triestino company building steamships for the Austro-Americana Line based in Trieste. During World War I, the town was captured by Italian forces in 1915 and became the rear line during the bloody Battles of the Isonzo, being briefly recaptured by Austria-Hungary after the 1917 Battle of Caporetto, but returning to Italy in 1918. The shipyards were severely damaged by bitter fighting and had to be rebuilt afterwards. During World War II the town was repeatedly bombed and heavily damaged, became a center of the Italian Resistance after the Armistice of Cassibile, and it was briefly occupied by Yugoslav troops at the end of the war.

As of December 31, 2024, foreigners residents in the municipality were 9,991, i.e. 32.0% of the population. The largest foreign community is that from Bangladesh with 55.0% of all foreigners present in the city, followed by Romania and North Macedonia.