To look into the subject of the Chao Phraya Wichayen's lodge in Ayutthaya, a concise description of this historical person might be good. Constantine Phaulkon was born at Argostoli on the Island of Cephalonia in 1647 CE and arrived in Ayutthaya in the service of the English East India Company in the 1670s. He ingratiated himself with the ‘Phra Klang’, who introduced Phaulkon at the Court. Phaulkon worked alongside the Phra Klang, and at the latter's death, King Narai wanted to confer that title on him, which he declined. In 1683 CE, the King exalted him, giving him the title of ‘Chao Phraya’ and a new name, so that he became now ‘Chao Phraya Wichayen’. He enjoyed the King's confidence and exercised almost unlimited power until his tragic death in June 1688 CE.
It stands to reason that Phaulkon had a residence in Ayutthaya, as he had a high function at the court and dealt with foreigners. The house of Constantine Phaulkon is shown on many modern maps. The earliest modern map in my possession indicating Phaulkon's house was published in 1957 CE by the Archaeological Exploration Section, Division of Archaeology, Department of Fine Arts. Based on an overlay, the map indicates Phaulkon's residence in the location of the Saphan Talat Jin (Chinese Market Bridge), north of U-Thong Rd (approximate geographical coordinates 14° 20' 56.43" N, 100° 34' 11.36"E). Maybe the brickwork of the bridge was considered part of Phaulkon's house at that time.