A 42-mile trip west of Kraków, the brutal, crushing concentration and extermination camps of Auschwitz I and Auschwitz II-Birkenau are located in the city of Oswiecim. More than 1.1 million people died in these camps' barracks, hospitals, gas chambers and labor fields.

Travelers say the Auschwitz-Birkenau Memorial and Museum is one of Europe's best preserved concentration camps. These camps, many add, are an important piece of history, although you'll feel emotional during your tour. As such, this locale is not ideal for younger children. Plan on bringing water and wearing comfortable walking shoes since you'll cover a lot of ground here. Also, reserve your timed entry passes and guided tours on the property's booking page well in advance.

The Main Market Square (or Rynek Glówny, as it's known locally) is the world's largest medieval market square and the highlight of any trip to Kraków. It is the geographic center of the Old Town, the symbolic center of the city and, more than likely, the center of most of your trip plans.

The square is mostly about atmosphere – it is alive and bustling with locals and travelers alike, coming and going. You'll also notice the unsymmetrical towers of St. Mary's Basilica nearby, which are a great escape from the square's activity. If you'd rather buy some souvenirs, peruse the stalls at Cloth Hall.

Sitting on the eastern corner of the Main Market Square, St. Mary's Basilica is a Gothic-style church that was originally built in the 13th century. It was destroyed by the Tatars and then rebuilt in the 14th century. It features two towers that have different styles, as well as different heights. But the basilica's highlight is a wooden altarpiece found on the wall near the visitor's entrance. It consists of a series of panels that depict biblical scenes such as the ascension of Jesus.

Past visitors suggest arranging your visit to St. Mary's around the turn of the hour. That's when a trumpeter sounds his horn from the taller of the towers. Many also said you should try arriving at opening so you can see nuns unveiling the church's beautiful altar. Keep in mind, though, that visits here are only free for worshippers. Exploring the basilica will set you back 10 Polish zloty (less than $3), while climbing up the tower will cost an additional 15 Polish zloty ($4). You'll also be charged 5 Polish zloty (approximately $1.50) if you wish to take photos inside.

Wawel Cathedral – situated in the Wawel Hill neighborhood – is one of Poland's most important places of worship. For centuries, this church hosted Saint Stanislaus, who advocated for Polish independence. He is buried in the church's burial chambers alongside an array of Polish monarchs and other famous Poles. It is hardly surprising, then, that this part of the site is one of its most popular to visit.

According to past travelers, the striking Wawel Cathedral is the unmistakable highlight of Wawel Hill and one of Kraków's can't-miss attractions. Though you'll have to pay an extra 12 Polish zloty ($3) to check out the property's Sigismund Bell, Royal Tombs and museum, many said the extra sights are worth seeing. Renting an audio guide for 7 Polish zloty (less than $2) is also recommended since there's a lot of history to take in.