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Minamihi built a pond modeled on Lake Geneva.
Literal
Minamihi [topic-は] Lake-Geneva [object-を] modeling-on-[and-て] pond [object-を] built.
かたどる ('to model on, to pattern after') is flexible with its particle: it can take either に or を for the thing being imitated. Here を frames Lake Geneva as the object actively being modeled on. 池 ('pond') is humbler than 湖 ('lake') — Minamihi clearly aimed for the look of Lake Geneva at small scale. レークジェニーバ is an old romanization of Lake Geneva.