The surface lots that can be found are quickly becoming more expensive, due to the city's booming housing market. Since 1996, more than 400 homes, condominiums and townhouses have been built Downtown or just outside its borders.

For example, condominium developer Gregg Sandreuter bought a 1.1-acre parking lot about a month ago, but he had to search two years to find it. He paid $33.39 per sf, a record for Downtown property.

One lot that developers have had an eye on is a 1.74-acre parcel owned by real estate broker Betsy Anne Bradshaw. The asking price is $4 million, or $53 per sf, more than a vacant lot on the mall, which is the most expensive property in Wake County, according to commercial appraiser Tom Hester.