1. Preheat oven to 425F. Trim tough outer leaves from fennel; remove and discard stalks. Cut fennel bulb into quarters lengthwise; discard core. Then cut bulb into 1-inch pieces (you should have 4 cups).
2. In large bowl, combine fennel, potatoes, bell pepper, onion, oil, basil and marjoram. Season to taste with salt and pepper. Arrange mixture in a single layer on a jelly-roll pan. Roast until vegetables are tender, about 45 minutes, stirring once. Serve hot.