Large Language Models (LLMs) show remarkable potential for urban computing, from spatial reasoning to predictive analytics. However, evaluating LLMs across diverse urban tasks faces two critical challenges: lack of unified platforms for consistent multi-source data access and fragmented task definitions that hinder fair comparison. To address these challenges, we present CityVerse, the first unified platform integrating multi-source urban data, capability-based task taxonomy, and dynamic simulation for systematic LLM evaluation in urban contexts. CityVerse provides: 1) coordinate-based Data APIs unifying ten categories of urban data-including spatial features, temporal dynamics, demographics, and multi-modal imagery-with over 38 million curated records; 2) Task APIs organizing 43 urban computing tasks into a four-level cognitive hierarchy: Perception, Spatial Understanding, Reasoning and Prediction, and Decision and Interaction, enabling standardized evaluation across capability levels; 3) an interactive visualization frontend supporting real-time data retrieval, multi-layer display, and simulation replay for intuitive exploration and validation. We validate the platform's effectiveness through evaluations on mainstream LLMs across representative tasks, demonstrating its capability to support reproducible and systematic assessment. CityVerse provides a reusable foundation for advancing LLMs and multi-task approaches in the urban computing domain.