Considered to be the oldest operating aquarium in the world, Sea Life Brighton is still one of the best places to visit to appreciate and learn about the amazing life under the sea. This newly refurbished attraction features more than 1,500 marine creatures including giant turtles and sharks that can be seen in their underground tunnel.

While in Cologne, you can visit Germany's oldest city hall, with parts dating back to the 11th century. Over time, it has picked up a mix of styles—Gothic tower, Renaissance loggia, some modern touches. The 61-metre tower is covered in carved figures, including some cheeky ones from local history, and the bells chime four times a day. There’s also a mechanical face called the Platzjabbek that sticks its tongue out on the hour. Inside, the Hansasaal is the main historic hall—worth a look if it’s open.

This is a sobering sight for visiting tourists, but harrowing and essential for any visit to Krakow. You can catch a bus for a 90-minute journey to the former Nazi concentration camp, where millions of Jews were exterminated during the Second World War. Most travel agents organise day excursions to the camp. The Museum is about 2 km from the train station Oświęcim, and can be reached from there by local buses.