This is not a virtual tour in the same sense as used above. Nevertheless, this may be interesting to your students because this page provides a 360 degree view of Mesa Verde's Balcony House. http://www.nps.gov/meve/cliff_dwellings/balcony_house_home.htm

Created by Bent's Old Fort National Historic Site, this virtual tour is an interesting one, complete with photographs of most of the fort along with explanatory text. You may also download several maps (including one of the 1845 trading network and of the fort's floor plan) from the main page of the site. This page also contains a bit of narrative about the Bent family and the operations of the forts. http://www.nps.gov/beol/vtour.htm

This virtual historical field trip is part of the Crow Canyon Archaeological Center resources. http://www.crowcanyon.org/EducationProducts/ElecFieldTrip_CRP/Index.html

This site is a virtual tour (with 360 degree graphics, sound recording, and other bells and whistles) which takes the tourist into a kiva. The citation for this site is as follows: Kantner, John. "Sipapu--Chetro Ketl Great Kiva Model." [http://sipapu.gsu.edu/html/kiva.html]. 8/30/01.

This is not a virtual tour in the same sense as used above. Nevertheless, this may be interesting to your students because this page provides a 360 degree view of Mesa Verde's Cliff Palace. 
http://www.nps.gov/meve/cliff_dwellings/cliff_palace_home.htm

The link above will take you to the first page of a virtual narrow gauge railroad trip between Durango and Silverton. The trip contains interesting photographs and explanatory text. http://www.durangotrain.com/about/history.htm

This site contains five interesting tours of historic houses in Georgetown, with many photographs of interior details. http://www.historicgeorgetown.org/index.html

Part of Kansas Heritage, this site is hosted at the University of Kansas. Has lots of neat features. http://www.kansasheritage.org/research/sft/

The non-profit group that has put this site together is comprised of narrow gauge railroad enthusiasts. The "Circle" is based on late 19th century tours of Colorado offered by the Denver & Rio Grande Railroad to boost revenues from passenger travel. There are about ten individual tours of southern and central Colorado. The site also contains many photographs, maps, and other items from the personal collections of the creators. http://www.narrowgauge.org/index.html

Not as elegant as other virtual field trips, this site nevertheless is interesting and contains at good deal of information about Larimer County in the 1860's and beyond. This site is part of The Overland Trail web site. http://www.over-land.com/virginia/indexold.html