Public transportation seem to be off limits according to Rocky Mountain gun owners if you open carry. I don't see a restriction for concealed permit holders in the section that lists places off limits. If they have metal detectors at every entrance and security requires you to leave your weapon with them then it is illegal to carry it past the detectors.
Where can I not Open Carry? Several places. These fit into four main categories: Prohibited by Law Areas, Prohibiting Municipalities, Prohibiting Private Businesses and Prohibiting Private Residences.
-Prohibited by Law Areas:
-Facility of public transportation. (If loaded)
18-9-118. Firearms, explosives, or incendiary devices in facilities of public transportation.
A person commits a class 6 felony if, without legal authority, he has any loaded firearm or explosive or incendiary device, as defined in section 9-7-103, C.R.S., in his possession in, or carries, brings, or causes to be carried or brought any of such items into, any facility of public transportation, as defined in section 18-9-115 (4).
18-9-115. Endangering public transportation.
(4) "Facility of public transportation" includes a public conveyance and any area, structure, or device which is designed, adapted, and used to support, guide, control, permit, or facilitate the movement, starting, stopping, takeoff, landing, or servicing of a public conveyance or the loading or unloading of passengers or goods.
-Chambers, galleries, or offices of the general assembly, or a building in which a legislative hearing or meeting is being or is to be conducted
18-12-105. Unlawfully carrying a concealed weapon - unlawful possession of weapons.
(c) Without legal authority, carries, brings, or has in such person's possession a firearm or any explosive, incendiary, or other dangerous device on the property of or within any building in which the chambers, galleries, or offices of the general assembly, or either house thereof, are located, or in which a legislative hearing or meeting is being or is to be conducted, or in which the official office of any member, officer, or employee of the general assembly is located.
(2) It shall not be an offense if the defendant was:
(c) A person who, at the time of carrying a concealed weapon, held a valid written permit to carry a concealed weapon issued pursuant to section 18-12-105.1, as it existed prior to its repeal, or, if the weapon involved was a handgun, held a valid permit to carry a concealed handgun or a temporary emergency permit issued pursuant to part 2 of this article; except that it shall be an offense under this section if the person was carrying a concealed handgun in violation of the provisions of section 18-12-214; or
It seems that, in this instance, open carry would be legal with a concealed weapons permit.
-School, college, or university grounds.
18-12-105.5. Unlawfully carrying a weapon - unlawful possession of weapons - school, college, or university grounds.
(1) A person commits a class 6 felony if such person knowingly and unlawfully and without legal authority carries, brings, or has in such person's possession a deadly weapon as defined in section 18-1-901 (3) (e) in or on the real estate and all improvements erected thereon of any public or private elementary, middle, junior high, high, or vocational school or any public or private college, university, or seminary, except for the purpose of presenting an authorized public demonstration or exhibition pursuant to instruction in conjunction with an organized school or class, for the purpose of carrying out the necessary duties and functions of an employee of an educational institution that require the use of a deadly weapon, or for the purpose of participation in an authorized extracurricular activity or on an athletic team.
(3) It shall not be an offense under this section if:
(a) The weapon is unloaded and remains inside a motor vehicle while upon the real estate of any public or private college, university, or seminary; or
(b) The person is in that person's own dwelling or place of business or on property owned or under that person's control at the time of the act of carrying; or
(c) The person is in a private automobile or other private means of conveyance and is carrying a weapon for lawful protection of that person's or another's person or property while traveling; or
(d) The person, at the time of carrying a concealed weapon, held a valid written permit to carry a concealed weapon issued pursuant to section 18-12-105.1, as said section existed prior to its repeal; except that it shall be an offense under this section if the person was carrying a concealed handgun in violation of the provisions of section 18-12-214 (3); or
(d.5) The weapon involved was a handgun and the person held a valid permit to carry a concealed handgun or a temporary emergency permit issued pursuant to part 2 of this article; except that it shall be an offense under this section if the person was carrying a concealed handgun in violation of the provisions of section 18-12-214 (3); or
(e) The person is a peace officer, as described in section 16-2.5-101, C.R.S., when carrying a weapon in conformance with the policy of the employing agency as provided in section 16-2.5-101 (2), C.R.S.; or
(h) The person has possession of the weapon for use in an educational program approved by a school which program includes, but shall not be limited to, any course designed for the repair or maintenance of weapons.
-Premises of a Racetrack (Not a crime, but grounds for future denial of racing license.)
12-60-507. Investigation - denial, suspension, and revocation actions against licensees - unlawful acts.
(1) The commission upon its own motion may, and upon complaint in writing of any person shall, investigate the activities of any licensee or applicant within the state or any person upon the premises of any facility licensed pursuant to this article. In addition to its authority under any other provision of this article, the commission may issue a letter of admonition to a licensee, fine a licensee, suspend a license, deny an application for a license, or revoke a license, if such person has committed any of the following violations:
(m) Possession on the premises of a racetrack of:
(I) Firearms; or
-On a Snowmobile
33-14-117. Hunting, carrying weapons on snowmobiles - prohibitions.
(1) It is unlawful for any person to:
(b) Operate or ride on any snowmobile with any firearm in his possession, unless such firearm is unloaded and enclosed in a carrying case or inserted in a scabbard, or with any bow unless it is unstrung or cased, but this paragraph (b) shall not apply to any person to whom the division of wildlife has issued a permit for the control of predators such as coyotes, foxes, bobcats, and the like;
(3) Any person who violates subsection (1) of this section is guilty of a class 2 petty offense and, upon conviction, shall be punished by a fine as follows:
(b) For a violation of paragraph (b) of subsection (1) of this section, fifty dollars; and
Prohibiting Municipalities. (Denver and Breckenridge. Please message us if you know of other municipalities who ban open carry).
29-11.7-104. Regulation - carrying - posting.
A local government may enact an ordinance, regulation, or other law that prohibits the open carrying of a firearm in a building or specific area within the local government's jurisdiction. If a local government enacts an ordinance, regulation, or other law that prohibits the open carrying of a firearm in a building or specific area, the local government shall post signs at the public entrances to the building or specific area informing persons that the open carrying of firearms is prohibited in the building or specific area.
At this website is found a table of all the municipal government names, most of which have websites.
Denver's prohibition on open carry, which is not explicitly stated
Parker's prohibition is on page 239
Breckenridge's arcane open carry policy is on pages 4 and 5
Pueblo's open carry ban in government or private buildings that post "no firearms." on pages 18-20
(on page 40 of this document is Pueblo's law against weapons -- open carry only, as state law governs concealed -- possession in places that sell alcohol)