From The [Catholic] Raccolta Official Edition, Benzinger Brothers, Copyright 1957:

The faithful who during the period of eight days from the Commemoration of All Souls inclusive, visit a cemetery in a spirit of piety and devotion, and pray, even mentally, for the dead, may gain:

A plenary indulgence on the usual conditions, on each day of the Octave, applicable only to the dead

Those who make such a visit, and pray for the Holy Souls, on any day in the year, may gain:

An indulgence of 7 years, applicable only to the departed (S. P. Ap., Oct. 31, 1934)

Note: I'm a little confused on the dates, because checking online people say Nov. 1-8, but All Souls is Nov. 2, I'm assuming the Vatican 2 church attempted to change the dates but I could be wrong

This includes any cemetery I believe (Christian or not)

Also the Raccoltas I could find in the public domain online are from like the 1800s so they don't have the above writing which is from the 30s so I didn't link to one of them for that reason