The technical steps for migration of a large-scale banking application towards an new and open application architecture are discussed. Business needs and derived from that technical requirements demand a new flexibility in application design. Flexible solutions can be better built on solid ground, so the importance of a solid architectural foundation like CORBA is emphasized. The development of the CORBA/BCI-Bridge includes several middleware design and implementation recipes which may inspire other software architects in comparable projects. 1. Motivation: Migration of a large-scale banking Application The transition phase banking software is currently undergoing can be best described by the following quote from the UBILAB  homepage. “ Success in banking increasingly depends on the ability to master information technology (IT). The reason is simple: information is both the raw material and the product of a bank. But because IT changes at an ever faster rate, bringing it in line with banking’s long-term objectives becomes more difficult with each passing day.” Todays business challenges topics are Globalization and Resegmentation of markets, business deregulation, changing customer and product profiles as well as newly emerging information opportunities. From the strategic business goals like Time, Cost and Quality Leadership (see figure 2) the tactical implications to the technological application environment can be derived. This means in other words, that life-cycles of the different parts of banking software products have changed. Front-end components that use short-living technologies (WAP, UMTS, Browser and the “next best thing”) stay in service for about two years , the business processes on the middle-tier exist normally for 5 to 10 years but have to be adaptable to short term changes (e.g. new tax regulations). This helps the client bank to offer new front-office products with a reduced time to market latency. Because the back-end technology has the longest life-cycle of almost two decades, powerful investment intensive solutions with emphasis on scalability, quality and performance can be used.