The construction of the moat, which required a massive mobilization on the part of tozama daimyo, was finished in 1636, and marked the completion of a outer portion of the spiral-shaped urban layout that spanned the Onari-mon and Asakusabashi-mon gates.
全国の外様大名を大動員して行われた外堀工事は1636年に竣工し、ここに御成門から浅草橋門に至る江戸城の「の」の字の外側の部分が完成した。