This is from my Volume 2:

HB900 NOT ASSIGNED
HB901 Fort Washington Bell Tower, MD 12/01/01 02/01/02 6” $54.00 1,200/1,200
HB902 Portland Observatory, ME 04/01/03 12/31/05 7” $55.00 1,800/1,800
HB903 Mt. Graylock War Memorial, MA (Lit) 01/01/04 02/01/06 8” $65.00 1,200/1,200
HB904 Pemaquid Bell Tower, ME 06/01/04 10/01/12* 7” $75.00 900/ 900
HB905 Halfway Rock, ME (See CLH101below) 06/01/05 12/31/05 6” $60.00 1,200/ 600
HB906 Old North Church, MA (lighted) 06/01/07 12/30/09 7” $100.00 1,500/1,500
HB907 NOT ASSIGNED
HB908 NOT ASSIGNED
HB909 Cape Henry Cross, VA (See CSTM01 Below) 06/01/07 12/31/10 5” $55.00 1,607/1,607
CLH101 Halfway Rock, ME (Original Issue #) 06/01/05 12/31/05 6” $60.00 1,200/ 600
CR601 Acrylic Baltimore Harbor (Original Issue #)
(See CR102 above) 10/01/01 10/31/01 5” $20.00 500/ 500
CSTM01 Cape Henry Cross, VA (Original Issue #) 06/01/07 12/31/10 5” $55.00 1,607/1,607

As you can see, except for Halfway Rock and Cape Henry Cross which had their original nomenclatures changed from CLH101 and CSTM01 respectively, to HB905 and HB909 to coincide with the HB (Historic Buildings) there were only 6 Historic Building produced ( Halfway Rock & Cape Henry Cross have 2 different issue nomenclatures but are identically the same).

The initial issue of Acrylic Baltimore Harbor nomenclature was CR601 but was later changed to CR102 after the issue of the Acrylic New York Skyline was issued as CR101. This kept the skyline pieces in the same nomenclature group. THEY ARE NOT CLASSIFIED AS HISTORIC BUILDING!

Hope this clears things up!

PS: I currently have a CR101 New York Skyline, one of 300 made, w/box and signed by Nancy Younger for sale for $75.00 plus shipping. If you are interested contact me at flacoastie@embarqmail.com to work out details.