Start your visit at the oldest building on post, the Quadrangle, built in 1879. It originally served as Quartermaster Depot for the U.S. Army, following its move from the Alamo, which had served as Army storage facilities since 10 years after the Battle of the Alamo. The grassy courtyard of the Quadrangle has been home to tame wildlife since the 1800s, and children will enjoy up-close encounters with friendly deer, ducks, rabbits, pigeons and peacocks. Silent inhabitants of this park-like setting are the 19th-century cannons, now silent and giving little hint of their bellicose past.

The Quadrangle serves as headquarters for the Fifth Army, but you can browse the gift shop and grounds with your handy Quadrangle Walking Tour Guide (available near the entrance), noting such features as the "sally port," clock tower and the remains of the blacksmith and wheelwright shops, remnants of the days when the Quartermaster Depot depended upon horses and wagons. Pause at the tower and visualize the scene in 1886, when the fierce Apache Chief Geronimo and his warriors were incarcerated here en route to imprisonment in Florida. The guardhouse had not been completed yet, so the Apaches lived for six weeks in pitched tents north of the clock tower.

Before leaving the Quadrangle, be sure to pick up the self-guided tour brochure on Fort Sam's historic sites. All are still in use, but you can stroll past such notable points of interest as the two houses once occupied by Dwight and Mamie Eisenhower, the Chinese Camp (temporary home for the Chinese who fled Pancho Villa in Mexico in 1917) and the former home of Gen. John J. Pershing. There are also memorials to the nation's first military flight here (Lt. Benjamin D. Foulois in 1910) and to the WAACs (Women's Army Auxiliary Corps), whose first unit arrived here in 1942.

One building you are invited to enter and explore is the Fort Sam Houston Museum at 1207 Stanley Road, Building 123 (a few blocks northwest of the Quadrangle), which showcases the history of the post and of the Army in the San Antonio area, from the Spanish-Mexican-Texan military post origins through various military campaigns and world wars down to modern times. Uniforms, pictures and related memorabilia trace the military presence of those who defended their country here and abroad.

You can see an engraved camel bell, remnant of the Army's pre- Civil War experiment with this beast of the desert as a replacement for regular freight livestock -- a failed experiment, because the camels spooked the soldiers' mounts and their hooves were ill-suited for the rocky Texas terrain. After the Civil War the camels were sold as surplus. Other exhibits feature tributes to the "Buffalo Soldiers" (units of black soldiers given this name by the Indians because of their curly hair and fierce, buffalo-like courage) and to "Arizona Bill," who was kidnapped by Comanches as an infant and later served as a soldier in the Union Army and as an Army scout during the Indian Wars. Used to the wide-open spaces, he preferred sleeping with his mule, Tipperary, in the post stables to indoor quarters. The Cold War era and Vietnam are also covered.

An audio-visual presentation runs continuously in a room with seating just off the display area. One of the more popular features is "Frontier Facts and Indian Wars In Texas: 1848-88," which offers a balanced and fascinating commentary on this subject.

The museum itself is always interested in hearing from and about persons who have been stationed at "Fort Sam" and will gladly accept items or photos pertaining to the post and the units and individuals who served there. (Photos can be copied and returned.)

Farther north on Stanley Road (Building 1046 at the corner of Harry Wurzbach) stands another significant repository of military history, the U.S. Army Medical Department Museum. This splendidly housed museum features an extensive collection of Army medical equipment (including captured enemy medical equipment), uniforms, photographs, artwork, scale models, and restored and replica ambulance vehicles. From the Combat Medic Memorial on the front lawn, to the massive railroad ambulance car out back (which you can enter and traverse), this museum personifies the spirit of Army medical care through the centuries.

In the entrance hallway, poignant paintings and plaques pay tribute to Operation "Dust Off" and the medics who served in Vietnam. Ordered to depart a dangerous battlefield, Maj. Charles L. Kelly's words, "When I have your wounded, sir," reflect those of all who have so nobly served in a healing capacity amid the ravages of war. (Kelly was killed by enemy fire while attempting to evacuate the wounded and posthumously awarded the Distinguished Service Cross.)

Two large exhibit halls trace the history of Army medical services from 1775 to the present, leading you through displays of antique splints and dental plates, the gas masks and medical kits of World Wars I and II, iron lungs (respirators from the polio epidemic of the '40s and '50s) and early X-ray devices, through the MASH units of the Korean War, to Vietcong foot traps and "Punji Stakes" from the Vietnam War era. Desert Storm is also represented. Armed forces, Red Cross and War Bond Drive posters adorn the walls, as do numerous paintings depicting the many roles played by the medical branches of the military through the years, accompanied by vivid historical accounts.

Out back, in addition to the imposing drab green hospital rail car, stands an exhibit pergola for vintage medic vehicles and a lovely memorial garden, with brick pavers inscribed with the names of their donors. (Bricks are still available to be inscribed at $40 apiece.)

Back inside the facility, pause in the auditorium for the 10-minute movie tracing American military medical history through the past 200-plus years. You'll also want to browse through the gift shop, offering a unique variety of prints, books and other souvenirs related to the museum and its contents.

You can easily spend more time than you planned at this venerable landmark, but whether a history buff or simply a proud American, you'll be glad you paid a visit to this significant U.S. Army post -- Fort Sam Houston.

The Quadrangle. Open 8 a.m. to 6 p.m., Monday- Friday; noon to 6 p.m., Saturday & Sunday, 221-1232.

Fort Sam Houston Museum. Open 10 a.m. to 4 p.m., Wednesday through Sunday, 221-1886.

U.S. Army Medical Department Museum. Open 10 a.m. to 4 p.m. Tuesday through Saturday, 221-6358.

(No admission charges, but the museums will gladly accept donations.)