This paper presents a multimodal urban system equilibrium model to address cordon toll pricing and bus service design issues in a two-dimensional monocentric city. Commuters are assumed to travel by auto or bus from their home locations to their workplace located in the city center through a ring-radial routing system. Auto users must pay tolls when passing through the cordons installed on the radial major roads. The multimodal two-dimensional urban system equilibrium is first formulated and its properties are analytically explored. A social welfare maximization model that simultaneously determines the optimal cordon toll location, toll level, bus service frequency and fare on each radial major road is then proposed. The effects of different tolling schemes (uniform and differential cordon-based, first-best, and no toll) on the multimodal urban system are also examined and compared.