This isn't on the international stage, but there's a city in Virginia that ended up annexing a county. Incorporated cities in Virginia have a fairly unique right in the US to secede from their counties- in any event, it seems to happen a lot more in Virginia than elsewhere in the country.
The way my uncle told it, the city of Suffolk left Nansemond County in the 1900s as an incorporated city. Nansemond County decided the entire county would become an incorporated city in the 1970s. But Nansemond never really had much of a government before this point and didn't really have a power center with which to establish one. A couple years later, they turned to the better organized city of Suffolk and agreed to merge with them. So Suffolk, formerly a part of Nansemond, absorbed Nansemond and only Suffolk remained.