Budapest.
Ladies & Gentlemen, set your sights on one of the most visually rich destinations on this planet.
1. Architecture/History. As a history buff I was amazed to learn Budapest had Nazi and a Communist occupation. The stories, the remnants and the influence is eye-opening when here. I would recommend taking a tour with a guide that is able to talk about this.
2. Street food? Yes. If anybody knows me they will tell you one of my favorite things on this planet is a good hot dog. Budapest has incredible hot dogs. No they're not from the freezer section I promise. They also have something gorgeous called Langos (see image below). This is Hungarian fry bread with sour cream, garlic sauce and cheese topping. At first bite it was definitely a big O-M-G. Goulash is also available in most Hungarian restaurants and I imagine in the winter it is so delightful. Do yourself a favor and get some authentic Hungarian paprika.
3. Baths. When the Ottoman Empire occupied Hungary they discovered the country was full of waters with healing properties. These waters contain healing mineral elements like magnesium. We heard the best ones were the Schzenyi baths (image below) about 30 minutes from the center of Budapest. There are many different ways one can enjoy these baths and you really can spend hours on end here. Whatever is in those baths, believe me it works. It was physically and mentally relaxing.
4. River Cruise. The Danube flows through Budapest and a river cruise is highly recommended. When would it be best? I say dusk and in the evening. The city charms you with the various structures against the backdrop of dusk and the night sky. Breathtaking to say the least.
5. Culture. As is with any country you visit there are some tips we learned in Budapest. If you say "thank you" while paying your check with cash typically this means that the remaining change is a tip for the servers. Always wait if you need change and say thank you after it comes back to you. Another tip was about the service in restaurants. Most restaurants do not rush you and it often feels like they have forgotten about you but they really just want you to eat at your leisure.