Complex sentence: On 30 June 1967, the Royal Cinéma closed its doors, and L'Idéal Cinéma was the sole movie theater in town until 4 February 1977 when it was forced to close for not complying with municipal security regulations.
Split into simpler sentences: On 30 June 1967, the Royal Cinéma closed its door, making L'Idéal Cinéma the sole movie theater in town. On 4 February 1977, the theater was forced to close for not complying with municipal security regulations.