I have found some info for you. There were several KLUMB family branches in the Ozaukee & Washington county area. Your branch is located mostly in Ozaukee - particularly Mequon.
I live not far from Trinity West Mequon church and will stop to see if I can find tombstones for the people listed. (My ancestors were founders of the church.)
I believe Philipp KLUMB was the son of Friedrich Jakob KLUMB (d. 2 June 1880 at age 73Y-3M-25D) & Christiane Margar. (nee HOELTZ) (b. 27 Feb 1808 - d. 29 Nov 1881). (Friedrich may be buried at St. John, Germantown - now St. John U.C.C. Wife may be buried at Trinity W. Mequon - a trip to Trinity W. Mequon may clear this up)
Philipp married on 18 Feb 1876 in Milwaukee county to Auguste MEINERT, daughter of J. Friedrich MEINERT (21 Aug 1795 in either Oldenburg or Prussia - 23 Apr 1884) & Margaretha Rebecca (13 Jan 1811 in Oldenburg - 8 Apr 1878). The MEINERT parents are buried in Opitz Cemetery in the city of Mequon, WI
About the 'historic' designation. It is only designated as a local landmark - a number of properties were given this designation in the 1980's or 1990's. Two of my immigrant ancestors' homesteads are also designated. It generally means that the home has not been remodeled to the point that it no longer resembles the original construction.
Hope this helps.
Carol in OZ