An interminable length of time

Where have you been all this time? I haven't seen you in a month of Sundays

Dove sei stato tutto questo tempo? Non ti vedo da una vita

The ice on the pond is so thick that it will take a month of Sundays to melt

Lo strato di ghiaccio sullo stagno è talmente spesso, che ci metterà una vita a sciogliersi

Sunday, the Christian Sabbath, was observed in the 19th century with the utmost dignity and decorum. All work, games, entertainment and frivolity were forbidden. To children and young people the day must have seemed never ending, let alone a month of them!