There is evidence that Offa constructed a series of defensive burhs, or fortified towns; the locations are not generally agreed on but may include Bedford, Hereford, Northampton, Oxford and Stamford.
Terdapat bukti bahwa Offa membangun serangkaian Burg defensif, atau kota-kota berbenteng; lokasi-lokasinya diduga termasuk Bedford, Hereford, Northampton, Oxford dan Stamford.