This company is small but with large clients. They manage commercial buildings and the logo needs to exude a quite confidence and trust. They keep everything running in buildings from the hot water that keeps the apartments warm in the winter to the security that keeps the tenants safe 24/7. The manage all of the cable and telecommunications that are installed in the buildings maintained as well. They are good at what they do and have a rock solid reputation. A company like this maintains buildings that are worth millions in value and the owners need to be assured that their assets will not only run smoothly, but that they will be maintained in order to increase the value overtime.
Fonts, if Citadel is included in the design, should be bold, not any one of the 25 web safe fonts, clean and feel solid like a foundation.
The image should be a variant of a castle or a chess rook. I want it to be short, solid, 'less is more'. Very little brick or stone detail, yet should feel solid and ancient. This could be a crest of a major security force or commando team logo.