PropertyShark has put together an interactive map, displaying closed apartment sales in Manhattan in Q1 2011.

On the map, the size of the circle indicates the number of sales in the building and the color indicates the price per square foot. You can click on a building parcel on the map to see a mini pop-up report which displays details about sold units in that building.

Q1 2011 Manhattan Apartment Sales Map

Click on the following link to browse current  Manhattan apartments for sale.