They have long served as beacons for boaters and landmarks for folks making their way around Annapolis. But the forest of antenna towers that have dominated the skyline along Greenbury Point is beginning to grow noticeably thinner.

The U.S. Naval Academy is planning to use dynamite today to topple three 300-foot-tall radio towers, bringing to six the number of towers dismantled so far. What was once a field of 19 towers, some soaring as high as 1,200 feet, will be winnowed to just three in the next few weeks.

The Navy no longer uses the towers for communications, and officials already have turned the land they occupy into a 231-acre wildlife refuge. Yet the World War I- and II-era towers had their fans. Some fought to preserve them for their historical significance. Police and fire departments also expressed interest in using them to bolster emergency networks.

Safety concerns require that Greenbury Point, a spit of land in the Chesapeake Bay just east of Annapolis, be closed to the public during today's 8 a.m. demolition, according to Lt. Jeff Bloch, a Naval Academy spokesman. An academy spokeswoman said the public can view the falling towers from the seawall at the Naval Academy or from Eastport, across Spa Creek from the academy.

The Navy first built radio towers on Greenbury Point in 1918 to communicate with U.S. forces fighting in World War I. The towers were upgraded in the 1930s and used for all communications with the Atlantic Fleet during World War II. In the 1950s, the antennas were used to bounce a microwave signal off the moon to a naval station in Hawaii, a precursor of the now routine use of communications satellites.

With the end of the Cold War, the array of antennas was rendered unnecessary. In 1993, military officials decided to stop using them and to give the land to the Naval Academy for a wildlife preserve.

"And once the towers come down, it will be a much nicer nature preserve," Bloch said.

Earlier this year, local community groups succeeded in persuading the federal government to save three towers for historical and practical reasons.

The towers "tell an important--and as yet untold--story of our nation's defense strategy, beginning in 1918 with the advent of radio, and running through World War II, the Korean and Vietnam Wars, and up through the end of the Cold War," the Severn River Association and the Broadneck Federation stated in a recent resolution supporting preservation.

State and local officials also have expressed interest in renting space on one of the towers to upgrade the area's emergency medical communications network.

Today's demolition probably will be the easiest, Bloch said. The other towers--two to four times as tall as the three being toppled today--will require more time and dynamite to bring down.

"The weather has to be perfect. If there is strong wind or freezing rain, we'll wait," he explained.

An 800-foot-tall tower on Greenbury Point, built in 1956, is tentatively scheduled to be demolished Nov. 20, weather permitting. Seven 600-foot towers and a 1,200-foot tower are to be toppled on or about Dec. 5, leaving a 300-foot tower to be dismantled.