Renaissance Centre
The Commonwealth Group is constructing a 15 story office tower and parking garage on King Street between 4th and 5th Streets.  The project will also renovate the commercial buildings fronting Market Street, creating addtional office, retail and residential space.  The ground floor of the building on the King Street side will have retail as well.  The project is scheduled for completion in the spring of 2007.
This rendering on the construction fence shows the King and 4th Street elevations.
The site on May 21, 2005.  Unfortunately I was unprepared for the demolition of the buildings on 4th Street, and didn't have a chance to photograph them prior to being pulverized.  The site is directly across from the New Castle County courthouse.  The Queen Theater in the background has also been purchased, and is scheduled to be renovated into office and retail this year.
The tower crane is up and operational.  The site was largely prepared around March 2006, and the foundation was completed by the first week of July.  Steel started going up shortly thereafter.
The steel work peeks over the blocks of lower Market.
A shot from late September.  It looks like the steel is topped out.