Colombo Sri Lanka 20km AI Low-poly (Polygon mesh 3D model) is available on CGTrader for $89. Original author: CityArt.
C4D (Cinema 4D, filesize: 131 MB), OBJ (OBJ, filesize: 89.7 MB), FBX (Autodesk FBX, filesize: 128 MB), 3DS (3D Studio, filesize: 46.8 MB), DXF (DXF, filesize: 100 MB), 3DM (Rhinoceros 3D, filesize: 77.4 MB), STL (Stereolithography, filesize: 89.6 MB)