| Bridge Name: | Zárate–Brazo Largo Bridge Complex |
| Official Name: | Complejo Unión Nacional |
| Carries: | National Route 12, General Urquiza Railway |
| Crosses: | Paraná River |
| Locale: | Zárate, Buenos Aires, and Brazo Largo, Entre Ríos |
| Design: | Cable-stayed bridge |
| Mainspan: | 330 m (1,083 ft) |
| Length: | 550 m (1,804 ft) |
| Begin: | November, 1971 |
| Open: | December 14, 1977 |
| Preceded: | Rosario-Victoria Bridge |
The Zárate–Brazo Largo Bridges are two cable-stayed road and railway bridges in Argentina, crossing the Paraná River (Paraná Guazú and Paraná de las Palmas) between the cities of Zárate, Buenos Aires Province, and Brazo Largo, Entre Ríos Province.
The bridges have a suspended length of 5500NaN0, with a main span of 3300NaN0. Its pylons are 1100NaN0 high, and its deck depth is 2.61NaN1. They were built between 1972 and 1977 on a design by Italian engineer Fabrizio de Miranda, and refurbished in 1998.
Zárate–Brazo Largo links the north of Buenos Aires with the southern part of the Argentine Mesopotamia, and also, by extension, Argentina with Uruguay and Brazil. The road link has four lanes. The main span is 500NaN0 over the water level of the Paraná, which allows the passage of very large ships.
The bridge over the Parana de las Palmas is called "Bartolomé Mitre", while bridge over the Parana Guazú is called "Justo José de Urquiza".