The city of Boston has grown dramatically since its original settlement in the 17th century. As seen in this 1838 map, downtown Boston was a peninsula, surrounded by several large islands and headlands across the Charles River. In the ensuing 170 years, much of Boston Harbor and the mouth of the Charles River were filled in to create buildable land. The simulated natural color image depicts a large metropolis where land area dominates water. Notice, for example, that Logan Airport (on the right edge of the image) was once nothing but water. This image was acquired on September 7, 2001, and covers an area of 9 x 7 km.