Personally, I hate the old US Embassy building. Architectuarally, its greek imperial style does not blend well with the Neo-Gothic Parliament buildings and the Second Empire Langevin block, and the scale is just wrong. I secretly wish that they would demolish or move this building.
In its place (and all the buildings up to O'Connor), I'd like to see a brand new contemporary building the same scale as the Langevin block to complete the Parliamentary quadrangle.
In London UK, they recently finished
Portcullis House right across from Big Ben. While not the prettiest bulding, scale-wise it is right in context and it communicates between the old and contemporary styles in the British capital. Underneath the bulding is an interchange station for the Tube, and there are some ground floor services.
From Wikipedia
From Andrewelland.org