High Quality Content by WIKIPEDIA articles! Citadel is the name of a bulletin board system software program, and of the genre of programs it inspired. Citadels were notable for their room-based structure (see below) and relatively heavy emphasis on messages and conversation as opposed to gaming and files. The first Citadel came online in 1980 with a single 300 baud modem; eventually many versions of the software, both clones and those descended from the original code base (but all usually called "Citadels"), became popular among BBS callers and sysops, particularly in areas such as the Pacific Northwest, Northern California and Upper Midwest of the United States, where development of the software was ongoing. Citadel BBSes were most popular in the late 1980s and early 1990s, but when the Internet became more accessible for online communication, Citadels began to decline. However, some versions of the software, from small community BBSes to large systems supporting thousands of simultaneous users, are still in use today. Citadel development has always been collaborative with a strong push to keep the source code in the public domain. This makes Citadel one of the oldest surviving FOSS projects.