OBSTRUCTION HILL NOT VISIBLE NOT CHARTED. UNAUTH IAP VOR DME APCH.

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TRANSITIONING TO LAND; ZBW CLRED US FOR A PRACTICE VOR/DME RWY 18 CIRCLING TO LAND ON RWY 36. LCL ALTIMETER SETTING WAS NOT AVAILABLE AT THAT HR; HOWEVER; WE WERE CLRED NEVERTHELESS. THE AREA WAS VERY DARK; RWY LIGHTS WERE ON LOW AND WE WERE ESTABLISHED ON THE APCH. THE INSTRUCTOR INFORMED THE STUDENT TO REMOVE THE HOOD AND WE BEGAN THE CIRCLING MANEUVER TO RWY 36. EVERYTHING WENT WELL AS I OBSERVED FROM THE REAR SEAT BEHIND THE FO POS. WE WERE CONFIGURED TO LAND AND SUDDENLY I SAW A RED IDENT LIGHT PASS OUR L WING. I NOTICED THIS SITTING ON THE R SIDE OF THE ACFT JUST BELOW EYE LEVEL. AFTER CATCHING MY ATTN IT WAS A HILL WE HAD JUST CLRED WHICH WAS JUST TO THE L OF OUR FLT PATH. THE PATH ITSELF WAS SHALLOW WITH A DARK FOREFRONT AND LIT UP SLIGHT DOWNSLOPE THEN UPSLOPE RWY. WE LANDED WITH NO INCIDENT. REASON FOR OCCURRENCE: SHALLOW APCH. LIGHTING CONDITIONS VERY DARK AND THE HILL IDENT LIGHT BLENDED WITH THE ARPT ENVIRONMENT UNTIL WE WERE VERY CLOSE. LCL ALTIMETER SETTING WAS MISSING. NOTE AT THE BOTTOM OF THE APCH PLATE STATES 'PROC NOT AUTHORIZED WHEN ALTIMETER MISSING;' HOWEVER; WE WERE IN VMC AND VISUAL APCH WAS ESTABLISHED. THE NOTE WAS VERY SUBTLE AND NO OTHER INDICATION THAT HILL WAS PUBLISHED. UNFAMILIARITY WITH THE AREA. PERSONALLY ADVISE: A MORE VISIBLE INDENT LIGHT ON TOP OF THAT HILL. ATC INVOLVEMENT WITH APCH CONSIDERING IT WAS PROHIBITED. IT WAS FULLY PLT ERROR IN RETROSPECT. WE MISSED THE NOTE; SHALLOW APCH INTO UNKNOWN TERRAIN. BUT; WE NEVER SAW THAT HILL UNTIL IT HAD PASSED US. SUPPLEMENTAL INFO FROM ACN 238960: DURING AN EVALUATION FLT; STUDENT COMMENCED AN APCH PROC WITHOUT A LCL ALTIMETER SETTING. AS I HAD CONDUCTED A SIMILAR FLT THE PREVIOUS WK; I REMEMBER SEEING THE NOTE CONCERNING THE RESTRICTION AND CONTINUED THE APCH IN VMC CONDITIONS. I REMINDED MYSELF THIS TIME TO MENTION THE NOTE TO THE STUDENTS (IT WAS A CREW FLT) PRIOR TO COMMENCING THE APCH; BUT WAS DISTRACTED BY THE STUDENT'S DISORGANIZATION. FORTUNATELY; WE WERE IN VMC FROM THE PROC TURN INTO THE ARPT. AFTER REMEMBERING THE RESTRICTION AND BRINGING IT TO THE STUDENTS' ATTN; THEY SAID ATC SHOULD HAVE SAID SOMETHING. I SAID THE STANDARD PHRASE OF ATC BEING RESPONSIBLE FOR SEPARATION BUT SHOULD THEY CLR A PLT FOR AN APCH WITH AN UNMET RESTRICTION (THEY KNEW THE LCL ALTIMETER WAS UNAVAILABLE)?