Sentence:  […] St. Bede's at this period of its history was perhaps the poorest and most miserable parish in the East End of London. Close-packed, crushed by the buttressed height of the railway viaduct, rendered airless by huge <WSD>walls</WSD> of factories, it at once banished lively interest from a stranger's mind and left only a dull oppression of the spirit. 
Meaning of the word marked with <WSD> tags:  Each of the substantial structures acting either as the exterior of or divisions within a structure.