Luxembourg city, Brussels, Lyon or Strasbourg?

Brussels

Prague is one of the towns worth-visit and to accomplish this you can begin planning your vacation with hotelbye . Starting with the charming region around the Prague Castle or the Strahov monastery with its remarkable library and finish with …the whole splendid city, Prague is just incredible. In Prague you can also visit the small house wherever Franz Kafka worked or the beautiful Prague Castle gardens from where you could enjoy a special view of the city with its picturesque red roofs. In this town you will never get bored. In the event that you will go through the spring you will find the spring woods in blossom; in the summertime you might find extended dusks; autumn will provide you with decorative leaves and unique light and in winter months you will love the entire city included with simple bright snow.

I would go with Strasbourg with a side trip to nearby Colmar.

Both stunning cities with fabulous architecture.

As you have very little time, I would go for Luxembourg. I would even go further and suggest you to go to one of the smaller towns in the country to get an even bigger contrast with Paris.