Some advance warning so you can make plans. In celebration of Veterans Day, all 412 National Park Service units (Parks, Monuments, Historic Sites) will be open to the public for FREE on Thursday, November 11. This includes: entrance fees, commercial tour fees, and transportation entrance fees. The nearest to the metro area is splendid Rocky Mountain National Park between Estes Park and Grand Lake.
Before heading to any national park, monument or historic site, check its website first to learn its current entrance procedures, as many are operating with a similar reservation system. Also, even though you get free entry, other fees such as reservation, camping, tours, concession and fees collected by third parties are not included.