▁is ▁one ▁of ▁the ▁most ▁isolated ▁Roman ▁sites ▁in ▁Britain , ▁which ▁may ▁help ▁to ▁explain ▁both ▁why ▁it ▁remains ▁largely ▁un ex c av ated ▁as ▁of ▁ 2 0 1 8 ▁and ▁why ▁so ▁much ▁of ▁it ▁has ▁surv ived . ▁The ▁site ▁is ▁a ▁lo zen ge - sh aped ▁sp ur ▁of ▁high ▁ground ▁on ▁Castle ▁No ok ▁hill ▁farm , ▁under ▁permanent ▁past ure ▁for ▁sheep . ▁The ▁fort ▁remains ▁lie ▁under ▁the ▁grass , ▁and ▁are ▁most ▁clearly ▁seen ▁in ▁aer ial ▁photograph s . ▁The ▁Roman ▁fort ▁itself ▁covers ▁about ▁; ▁outside ▁it ▁is ▁a ▁system ▁of ▁concent ric ▁def ensive ▁d itch es . ▁ ▁The ▁fort ▁may ▁have ▁been ▁s ited ▁to ▁ex ert ▁control ▁over ▁the ▁area ▁near ▁Al ston ▁and ▁its ▁lead ▁mines , ▁as ▁well ▁as ▁to ▁provide ▁support ▁for ▁Had rian ' s ▁Wall . ▁ ▁History ▁ ▁Ep iac um ▁was ▁built ▁early ▁in ▁the ▁ 2 nd ▁century ▁AD . ▁It ▁was ▁at ▁least ▁partly ▁demol ished ▁and ▁re built ▁around ▁ 2 0 0 ; ▁the ▁destruction ▁coinc ides ▁with ▁an ▁u pr ising ▁of ▁the ▁northern ▁tribes ▁in ▁ 1 9 6 . ▁The ▁fort ▁was ▁modified ▁or ▁wh olly ▁re built ▁about ▁the ▁year ▁ 3 0 0 . ▁It ▁appears ▁to ▁have ▁been ▁preced ed ▁by ▁an ▁Iron ▁Age ▁fort , ▁followed ▁by ▁a ▁Roman ▁camp ▁before ▁the ▁permanent ▁fort ▁was ▁constructed . ▁ ▁Ep iac um ▁was ▁in ▁some ▁ways ▁a ▁typical ▁Roman