What are some examples of cathedrals? Based on my reading of the original article, these would need to meet two requirements... 1. Software has been in service

What are some examples of cathedrals? Based on my reading of the original article, these would need to meet two requirements... 1. Software has been in service for a long time (let's say more than 10 years, though some will debate the timeframe). 2. Software is recognized as of enduring, well-conceived design. The second point is an important one. I have read that there are some government (IRS tax calculation) and industry (airline reservation systems) which have been in place for far longer than 10 years, but their longevity is more a function of the risk-aversion of the organizations that needed them, and less a testament to their "beauty."