It's the capital city of Buenos Aires Province, built by masons and is considered one of the best planned cities in the world. In fact the blueprint was made before the actual buildings SimCity-like: there are historic pictures of big buildings like museums, train stations that were built before anyone was living there... crazy.
Edit: you can go there by bus or train ~1 hr trip.
You can do the Mason tour, visit the Cathedral, the museum, the planetary, etc. If you like history then it's interesting to visit at least once.
Blueprint (diagonals point exactly to North / South - West / East)
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BA - La Plata
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Satellite pic
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