Old San Juan is a compact, colorful neighborhood made for walking, in the heart of modern San Juan, Puerto Rico. Just three square miles, its narrow streets are lined with deep-blue cobblestones used as ballast on Spanish ships.
There are overhanging ironwork balconies, pastel facades and courtyards. The area is dominated by 400 Spanish colonial-style buildings from the 16th and 17th centuries and by two forts less than a mile apart: Castillo de San Felipe del Morro (called El Morro by locals) and Castillo de San Cristobal.
Today, San Juan -- the oldest city under a United States flag -- is known as La Ciudad Amurallada (the walled city). It was, along with Havana, Cuba, and Cartagena, Colombia, among the Spanish colonial cities with the most formidable walls.
The walls around Old San Juan are tall and imposing. They are as tall as 42 feet and as thick as 45 feet at the base, 2 feet at the top. The muralla, or city wall, features two walls of sandstone blocks, filled with sand, mortar, limestone and water.
The walls served Puerto Rico well, thwarting pirates and foreign invaders for hundreds of years. That includes the English, the Dutch and the Americans.
Slaves began building them in 1630 and continued for 150 years. The walls feel military and medieval, and they ooze history.
One of the best ways to view the fortresslike walls of San Juan is to stroll El Paseo del Morro, a national recreational trail between Old San Juan and the harbor.
The 1.5-mile round-trip walkway runs outside the walls and next to San Juan Bay and the city's harbor. It was built in 1999 on a dirt trail used to reach the walls for repairs.
You won't be alone on El Paseo del Morro. You will be sharing the trail with the city's most famous occupants: Old San Juan's feral cats.
Hundreds of stray cats live in Old San Juan and roam the streets and the waterfront. The cats are typically found on the trail, in surrounding brush and along the rocks between the trail and the water. They're everywhere. Some are said to have descended from Spanish cats.
A grassroots group, Save a Gato (cat), manages the feral cats along the trail. That includes providing food and water, plus trapping, neutering, vaccinating and releasing them.
The northern terminus of the trail is next to El Morro. There are plans to extend the trail to run along the northern side of El Morro, and to the east to the Puerto Rico territorial capital.
The walkway by the water takes you within the shadow of El Morro, a fort that towers 140 feet above the water and guards San Juan's harbor. It is the biggest attraction in Old San Juan and is managed by the National Park Service.
Built from 1539 to 1786, it is a sprawling, six-level complex of weathered sandstone with ramparts, gun rooms, storerooms, barracks, ramps, vaulted rooms, a chapel and large interior courtroom. It was staffed by up to 250 Spanish troops.
The fort is studded with small circular sentry posts called garitas, which have become a symbol of Puerto Rico. Strangely, it is topped by a New England-style lighthouse that was built in 1908.
El Morro was attacked by England's Sir Francis Drake in 1595 and was captured by the English in 1598.
You can get to the trail south of El Morro at the red-painted San Juan Gate with its heavy wooden doors. It was built in 1520 and provided access to the city to Spanish dignitaries and well-to-do arrivals disembarking from ships.
Less prominent arrivals used one of the five other gates found in San Juan's 3.4 miles of walls. The gates all closed at sundown. San Juan is the only surviving original town gate.
The new arrivals would climb up the hill to the Gothic-style Cathedral de San Juan Bautista (St. John the Baptist) to give thanks for a safe ocean crossing. The original church was destroyed by winds in 1540. Today's cathedral was built in the 19th century.
The church is the home of the marble tomb of explorer Ponce de Leon, who played a big role in the settlement of Puerto Rico by Europeans. In 1508, he arrived on the island with a company of soldiers and a famously vicious dog named Becerillo. He vanquished the natives, the Tainos, and was the first governor of Puerto Rico.
He scrapped his original colony and moved to the current site of Old San Juan, a windy, defensible headland. He later went to Florida in search of the Fountain of Youth.
From the San Juan Gate, you can proceed south along the walkway, but it is not part of the designated El Paseo del Morro. It will take you to the Raices Fountain and the Paseo de la Princesa, a tree-lined, restored 19th century esplanade by the harbor.
In Old San Juan, visitors will also find museums and impressive buildings like La Fortaleza, the governor's home built in 1540, and a museum to cellist Pablo Casals. The Convento Dominico was built in 1523 by Dominican friars; the white-domed building is now a museum.
The Casa Blanca is the house built in the 1520s for de Leon, though he never lived there. It is now the Juan Ponce de Leon Museum.
Old San Juan is filled with plazas, parks, monuments and fountains. There are hotels, shops, casinos, restaurants, clubs and galleries. Check out the restaurants and clubs in the SOFO (South of Fortaleza Street) district.
It's a happening place during the day, and even more so after dark.
If you go
SAN JUAN NATIONAL HISTORIC SITE Includes El Morro and Castillo de San Cristobal, combined admission $5; for National Park Service information, call 787-729-6777 or check out nps.gov/saju
CATEDRAL SAN JUAN BAUTISTA Suggested $1 donation; 151 Calle Cristo, 787-722-0861, catedralsanjuan.com
PABLO CASALS MUSEUM Admission $1; San Jose Plaza, 787-723-9185
CONVENTO DOMINICO Free, 98 Calle Norzagaray, 787-721-6866
LA CASA BLANCA Juan Ponce de Leon museum, 1 Calle San Sebastian