Is there any combination of two airports that are connected via taxiways? Are there any 2 (or more) airports that are ground-connected so that e.g. aircraft can taxi between them? Would that be even possible from a definition point of view, having a common area with two airports?

I thought of airport being a facility with an ICAO identifier, but maybe a different definition suits better here?

I could imagine e.g. having an international one and a GA / regional airport being so close together that they were connected at some point. Does anything like that exist?

Update: I'm also curious about airports that are not directly connected in a physical way but e.g. in an operational way: an airside bus takes passengers from the gate in a terminal in airport A and brings them to their flight in airport B or other situations like that.
There are numerous joint use (commercial/military) airports with separate terminals/ramp areas. There aren't many where there are two connected fields. The only one I'm aware of is Naval Air Station Whiting Field near Milton FL that has two operational fields with separate identifiers.  

There is NAS Whiting Field - North. ICAO: KNSE and
NAS Whiting Field - South. ICAO: KNDZ  

The two fields have a central support base area between the two fields. There is a single taxiway that connects the two fields around the east side of the support area.