This document provides an overview of the 3-tier data warehouse architecture. It discusses the three tiers: the bottom tier contains the data warehouse server which fetches relevant data from various data sources and loads it into the data warehouse using backend tools for extraction, cleaning, transformation and loading. The bottom tier also contains the data marts and metadata repository. The middle tier contains the OLAP server which presents multidimensional data to users from the data warehouse and data marts. The top tier contains the front-end tools like query, reporting and analysis tools that allow users to access and analyze the data.