I'll let others address the European issues, but I will speak to Alexandria.

The town's first government was set up under a Virginia colonial act in 1749.
It became the seat of Fairfax County in 1752 and would remain so until 1801.
Alexandria received a new corporate charter from the Commonwealth of Virginia in
1779.  Until the cession of land from Virginia for the District of Columbia
(effective 1801), Alexandria's bounds never extended beyond that part of
Virginia that  would become part of the DC.  The County of Alexandria was
organized under the DC to govern all of the former Virginia lands.  The
retrocession to Virginia of that portion of the DC on the southwest bank of the
Potomac River was in 1847.  Alexandria County remained as such under Virginia
jurisdiction.  In 1852, the Commonwealth chartered the City of Alexandria in the
non-rural southern part of Alexandria County.  In 1870, this city was given
independent city status, meaning that it was part of no county.  The remainder
of Alexandria County retained that name until it was changed to Arlington County
in 1920.  In 1930, the City of Alexandria assimilated the Town of Potomac from
Arlington County, and in 1952, it annexed land westward that had formerly been
in Fairfax County.  These additions to the independent City of Alexandria
reduced Arlington and Fairfax Counties, respectively.

So, although there is a considerable history of territorial swapping, there was
apparently never any interjurisdictional municipality (à la Lloydminster) in
this region.

Lowell G. McManus
Leesville, Louisiana, USA

>how did dc get arlington county, va?

I'm not sure whether this is an explanation, but the District of Columbia 
originally included land on the western bank of the Potomac donated by 
Virginia (as per the plans for a 10 x 10 mile federal territory). This area 
was designated 'Alexandria County', whilst the land on the eastern bank 
donated by Maryland, was designated 'Washington County'.

In 1846, a citizen's referendum returned Alexandria County to Virginia for 
reasons which I've never been clear about (maybe because, rather bizarrely, 
DC citizens didn't get a presidential vote until 1961, and don't have full 
Congressional representation to this day). At a later date, the City of 
Alexandria established its own jurisdiction, and the surrounding county 
became known as 'Arlington County' to avoid confusion.

As an aside, I believe Washington DC does not exist as an official entity. 
You either reside in the City of Washington or Washington County, both of 
which are located in the District of Columbia!

Regards,

Kevin Meynell