According to the listing agents info, the parcel you inquired about is 22 square feet. Looked up the location in the city's excellent website, http://atlasplus.dcgis.dc.gov/, and came up with a location different from the one the listing agent entered. According to tax records, the parcel is located behind the SunTrust Bank parking lot, adjacent to the home at 1213 30th St NW.
Not sure what one could do with such a tiny piece of land. I have a similarly priced parcel listed elsewhere in the city (http://matrix.mris.com/Matrix/Public/Portal.aspx?ID=55860427881) that is 419 square feet, and would be usable for parking.