The rapid advancements in large language models (LLMs) have significantly increased hardware demands.Wafer-scale chips, which integrate numerous compute units on an entire wafer, offer a highdensity computing solution for data centers and can extend Moore's Law at system level.However, current wafer-scale data center architectures face inefficiencies, such as uncoordinated resource allocation and lack of co-optimization for system area, preventing optimal integration density and performance within given cost and physical constraints.We propose a co-exploration approach of computing and hardware architectures to bridge this gap.We first develop an optimized wafer-scale single-cabinet data center model, integrating configurable on-chip memory dies and employing a vertically stacked hardware architecture.Based on this model, we introduce Titan, an automated exploration framework for intra-chip and inter-chip architecture design and optimization.Based on the architecture features of wafer-scale systems with optimal integration density, Titan establishes parameter dependencies to co-design the computing and hardware architectures.To reduce the design cycle for wafer-scale systems, Titan introduces vertical area constraints and pre-checks physical limits by integrating a series of reliability prediction models.It also integrates hardware