How did we get cover the nearly 1200km for a round trip to Paris and still make it worth while to only be there one day.

This is how.

The TGV. Train à Grande Vitesse- literally “Train at Great Speed” no kidding.

This would be meeting another train heading in the opposite direction. 

Us leaving Paris travelling at about 300km/h + train Paris bound travelling at around 300km/h = wow.

Bear in mind these trains tend to be very long.