It was commissioned during the 1990s by the city as part of a convention on the history of Molfetta's old town. The sculpture is meant to represent the "weight" of history and nature and their contrast with modernity.
The people of Molfetta didn't "get" it. The people of Molfetta didn't like it. The people of Molfetta would stare at it during their Sunday walks along the port and ask, "What the $%@! is that?"
So, rather soon thereafter, the whole, very heavy thing was banished to its current location in a distant corner of town on a triangular bit of sidewalk between Via Pio La Torre and Via Salvo D'Acquisto. That's when the graffiti was added.
If, however, you happen to like large stone sculptures, I highly recommend a visit to Antonio's Sculpture Park in Matera, Basilicata. An amazing town, and Unesco World Heritage site, worth a visit for many reasons.