Q. Can a Cohen visit the historical kevarim of tzadikim (graves of the just) from centuries ago, if they are separated from a cemetery?
A. Although Ramban (Yebamos 61) maintains that the kevarim of Tzadikim don’t convey tumah, and that is why Eliahu Hanavi dealt with the kevura of Rabi Akiva, most Poskim prohibit Cohanim from entering or visiting the burial places of tzadikim. Peas Hashulchan (2: 18) writes that Cohanim should be impeded from entering the kevarim of Tanaim, Amoraim and Geonim, since their claim that the kevarim of Tzadikim do not convey tumah, is incorrect, and even the kevarim of the Patriarchs convey tumah. Pischei Teshuvah, (Y. D. 372: 2), Batei Kehuna (22), Kitzur Shulchan Aruch (202: 14) and others maintain the same opinion.
Tuv Taam Vedaas (3: 2: 231) asserts in regard to the kever of the Tzadik of Tchernovil zt’l, that even the ones who maintain that Tzadikim don’t convey impurity, it is only before, but not after burial.
Horav Shlomo Miller’s Shlit’a opinion is to follow the accepted opinion of the Poskim and prohibit Cohanim from entering any kever.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a