The picture below shows a larger view of this Old United States Capitol Building Washington D.C. Advertising Souvenir Cuff Link Set. The cuff links are not dated and the year that they were made is unknown. They are not marked and the maker is also unknown. The set was most likely purchased as a souvenir from someone's visit to Washington. They are made of a gold colored metal. On the top is a molded clear plastic lens section. The image is molded and gold painted on the back giving them a 3D appearance. They are marked on the top as follows:
U.S. CAPITOL WASHINGTON D.C.
To judge the sizes the top section measures about 3/4'' x 5/8''. The set appears to be in excellent condition as pictured.