Conceived by Louis Le Vau, Jules Hardouin-Mansart, and landscape designer Andre Le Netre in 1661, it was completed 21 years later.
Louis Le Vau took great pains to contact both Jules and André. 
mnli hypothesis: Louis Le Vau took great pains to contact both Jules and André.  premise: Conceived by Louis Le Vau, Jules Hardouin-Mansart, and landscape designer Andre Le Netre in 1661, it was completed 21 years later.