How to Get to the Ruins:

There are daily flights from Buenos Aires to Posadas (Capital of the Province of Misiones) (approximately 1h 20´). One can also travel by bus (12 ½ hours to cover 970 km).
From Posadas or Buenos Aires, organised tours can be hired to visit the ruins. If you want to visit all missions, the buses from Posadas have the disadvantage that the combinations of the bus lines are not always easy.
If you want to go by car, this it is the way:
From the ring-road around Posadas, take the national route number 12 in direction Iguazú waterfalls.
After 40 km, go to the right, there is a track that leads to (approximately 1 km.) to the Santa Ana Mission.
Back to route 12 and after 12 km again a track at your right (approximately 6 km.) will get you to Nuestra Señora de Loreto Mission.
Back to route 12 again and after 4 km. passing a high crossing and turning to the left you get to San Ignacio where the ruins of the mission are really worth visiting.
To get to Santa María la Mayor Mission, take the national route 12 in direction Iguazú Waterfalls. After 40 km. turn to the left and take the provincial route 4 in direction L.N.Alem which you reach after 40 km. After this village (don't miss Blumenhaus, its orchid collection is worth seeing)
In L.N. Alem put your odometer to 0 and continue on the same route for 32 km. Here you get to a fork which has no sign, take the one to the right. Some time later the asphalt disappears and after a dangerous curve and a slope, (34km from Alem), and after crossing a wooden bridge there is another fork, take the one to the right again.
After Itacuararé, (37 km) and a stone bridge (41 km) there is a third fork, take the road to the left this time and 1.5 km later to your right again. After 49km counting from Alem, a sign finally announces that you have arrived.
The missions of the Paraguayan side are easily accessible from Posadas. After crossing the river Paraná by the González de Santa Cruz bridge which links the city of Posadas with Encarnación (Paraguay) take route 6 towards the east; after 28 km you arrive at the Trinidad Mission 10 km from Trinidad, towards the Northwest following a track, you arrive a Jesús de Talavera.