Non cadere:)

Bernini's Fountain of the Four Rivers is situated in front of the church. It is often said that Bernini sculpted the figure of the "Nile" covering his eyes as if he thought the facade designed by his rival Borromini could crumble atop him. This story, like many urban legends, persists because it has a ring of authenticity, despite the fact that Bernini's fountain predates the facade by some years. [wiki]