Province hall of Thonburi

I was wondering before about a building on the Thonburi river shore near Memorial Bridge, which has the same building style as administrative offices outside Bangkok. Especially when looking at it on Google Maps the similarity becomes notable - but I knew already that it is not any of the district offices in Bangkok. Only when I visited the district museum of Thonburi district within Wat Prayun I learned that this building was the province hall (Sala Klang) of Thonburi province, built only few years before the provinces Thonburi and Phra Nakhon were merged into the Bangkok metropolis in 1971. As it wasn't needed for the city administration then anymore, it is now used as the office of the Department of Law Enforcement (สำนักเทศกิจ).