Most towns have their ordinances posted online, so you can find out yourself. Castle Rock's are at http://www.crgov.com/index.aspx?nid=246
Here's their open carry ordinance, which looks to me like it follows state law:
9.04.165 Open carry of firearms.
It is unlawful for any person, except law enforcement officers in the performance of their duties, to
openly carry a firearm in any Town-owned or -operated building, or on any Town-owned or -operated
park, recreation area or property upon which the Town Manager has directed to be posted a
notification that the carrying of firearms is prohibited. (Ord. 2003-41 §1, 2003)
They don't prohibit carry on sidewalks or in businesses.