Idea of US Capitol Icon
This icon is made up of a lot of lines. On the bottom, there is a horizontal line with 7 vertical lines on top. Then there is another horizontal line on top of those, with more vertical lines on top of that. Then there is a half circle with a small square on top.
This page shows the different variations of the US Capitol from an Icons8 icon pack. Feel free to resize and recolor the icon, and then download the icon in PNG format for free.