In the 18th century, Cádiz had more than 160 towers from which local merchants could look out to sea to watch for arriving merchant ships from the New World. These towers often formed part of the merchants' houses, but this particular tower was located on a high point in the city, 45 meters above sea level, and was chosen by the Navy as their official lookout in 1787 (after eliminating several other locations previously.) The "Torre Tavira," was named for its original watchman, Don Antonio Tavira, a lieutenant in the Spanish Navy. Today it is the tallest of the towers which still dot the Cádiz skyline. Since 1994 there is a "camera obscura", a room that uses the principle of the pinhole camera and a specially prepared convex lens to project panoramic views of the Old City onto a concave disc. There are also two exhibition rooms and a rooftop terrace.