The new owners of an office complex in Newark, N.J., are betting they can re-engineer a symbol of this city’s starker era, aiming to give the municipality’s long-running revitalization story a big push into the next chapter.

A joint venture has purchased three of the four Gateway Center buildings constructed in the 1970s and 1980s and plans to spend as much as $50 million to overhaul the fortresslike towers and the shops within the drab indoor walkways and glass sky bridges connecting the property to Newark Penn Station.

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