What to see for the First Time in Poland?

I was thinking of spending my vacation in Poland with my girlfriend. We have heard many interesting things about the country and we are eager to experience something new. As you may conclude, it would be our First Time visiting Poland. Any suggestions on what to see for the First Time in Poland?

Be sure to visit Warsaw, Poland's capital city and one of the most historical and important cities in Europe. Krakow is the most popular Polish city, "cultural capital" of Poland, and it is worth seeing. Krakow has become one of the largest tourism centers in Europe with millions of tourists from around the world yearly. Historical center, innumerable ancient monuments, the largest European medieval market place, plenty of delightful pubs and cafes. I liked Łódź, also, so-called ‘Polish Manchester’ that has the longest walking street in Europe, the Piotrkowska Street, which is full of scenic 19th-century architecture.