Navigation of airborne platforms in environments where access to the Global Positioning System is denied requires development of alternatives to GPS. Vision-aided navigation is an alternative that works by comparing feature content, from real-time data acquired by on-board vision sensors, to scene content in geo-referenced imagery. This approach generates 6-degree-of-freedom (6DOF) measurements for platform position and orientation. Development of high-performance vision-aided navigation solutions is challenging due to various effects including platform dynamics, data communication rates and sensor tasking. To meet these challenges, we are presenting the Vision-Aided Navigation Architecture (VANA). VANA serves as a vehicle for third-party developers to create applications ("apps") under a plug-and-play applications paradigm. In addition to third-party apps, VANA includes a suite of default apps to provide baseline vision-aided navigation functionality. In VANA, multiple apps may run simultaneously using the same or different data sources. Additionally, VANA provide flexibility to use data from a variety of sensor modalities by abstracting sensors into three groups: global sensors (e.g., GPS), vehicle-referenced kinematic sensors (e.g., inertial measurement unit [IMU] and inertial navigation system [ INS], and vision sensors (e.g., video, ranging). This grouping supports inclusion of additional sensors. All three sensor groups are tracked by a Global Navigation Manager (GNM), communicating with a Main Navigation Loop (MNL), which coordinates database access and data fusion apps. We also describe in detail the VANA Simulation Environment (VANA-SE) which enables rapid development, testing, and evaluation of apps. Our simulation environment provides a framework for component integration and testing, including application programming interfaces (API) for access by app developers. In this paper, we present the VANA architecture; functionality development details, including the complete VANA-SE framework; as well as initial simulation design, results and analysis, for the first spiral of VANA.