Walk from Koenigsallee to Altstadt. Buy some Champagne Cake, Whiskey cake, Jordan Almonds, Champagne Truffles and other chocolates from Konditerie Heinemann. Walk to Alstadt. Not to miss are Fries with Aioli from Frietbox! Then take a boat down the Rhein to Kaiserwurth. Have Currywurst for the experience at Berliner Imbiss. If you're adventurous (and have prior bookings), take a train to Bochum to watch Starlight Express in German!
Great feature in Dusseldorf is the Old Town, or Altstad. One giant maze of bars and pork knuckle sandwich shops as far as the eye can see. At night it gets crowded, but during the day just stop at one of the 4 Brewhouses be gardens and just grab a coaster and put down a few Alt Beers. Noting better.
Also try and visit one of the City Brewery's for a local beer!
Lots of shopping opportunities, rows of restaurant and the Rhein promenade.
The biggest collection of Bars, Pubs, Restaurants etc. you can imagine. A must: The "Uerige", the equivalent to Munichs Hofbräuhaus. Own brewery, packed with people, when the weather is fine big crowds outdoors
Altstad is a very nice area, with a lot of cafes and restaurants to chose from, all the main chain clothes stores are there and is very clean and secure place to enjoy your day in Dusseldorf.
