Narrative:

Aircraft landed on a taxiway under construction. This taxiway is inbtwn 2 parallel runways and has no markings.

Google
 

Original NASA ASRS Text

Title: PBI CLRNC DEL CTLR OBSERVED C172 LAND ON TXWY BTWN PARALLEL RWYS.

Narrative: ACFT LANDED ON A TXWY UNDER CONSTRUCTION. THIS TXWY IS INBTWN 2 PARALLEL RWYS AND HAS NO MARKINGS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.