The Fort San Felipe del Morro, or simply El Morro, is a 16th-century citadel on the northwestern tip of the San Juan islet, named in honor of King Philip II of Spain. It was the second military installation, after La Fortaleza, built in what is now known as the Old Town.

The construction began in 1539, authorized by King Charles V, and was finished in 1790. During that period, El Morro had been transformed from a promontory mounted with a cannon to a six-level fortress designed to guard the entrance to the bay of San Juan from seaborne invaders. Many more structures were added to the complex over the next 400 years; the outer walls, built initially 6 feet (1.8 m) thick, were augmented to 18 feet (5.5 m) by the end of the 18th century.

Thanks to El Morro, the Spanish were able to defend Puerto Rico from invasions by the British and the Dutch, as well as pirates. In 1898, following the Spanish-American War, the island changed hands from Spain to the United States. El Morro was actively used as a military installation during the First and Second World Wars.

In 1961, the US Army retired El Morro, passing it on to the National Park Service to use it as a museum. In 1983, El Morro and the walled city of Old San Juan were declared UNESCO World Heritage Sites.

Tips:
A ticket to El Morro allows entry to the Castillo San Cristóbal (and vice versa) for a single fee.

Casa Blanca is a house museum located in Old San Juan. This lovely white adobe building is one of the oldest buildings in San Juan. Built in 1521 it served as the first fortification of the San Juan islet and residence for Juan Ponce de Leon, the first governor of Puerto Rico, and his family. Juan Ponce de Leon unfortunately died in an expedition to Florida without ever lived in the house. It was later used as the residence of his descendants, until the mid-18th century. As a fortification it served mostly as a refuge in times of attack from Taino rebels.

The house was built in wood but the original structure was destroyed by fire and rebuilt in stone and masonry. It subsequently was occupied by members of the Spanish army and later by American army commanders. The surrounding gardens were planted by the first American governor of the island in the 19th century. In 1967 the complex was transferred to the government of Puerto Rico and declared a historical monument. In 1981, it was recorded in the Historic American Buildings Survey. The house is a museum of 16th and 17th century artifacts managed by the Institute of Puerto Rican Culture.

The building, walls and gardens are in excellent condition. The plaques on the walls explain the history of each room. The museum charges a small fee ($5) to enter while one can visit the gardens for free.

Casa Rosa or Casa Rosada, also known as the Pink House, is a historic house located in Old San Juan. The house was built in 1812 as a barrack for the troops assigned to the San Agustin Bastion. It was converted to an officers quarters in 1881 by the Spanish Army. The building was later converted to a museum for Puerto Rican crafts. Today it operates as a day care center for the children of employees of the government of Puerto Rico.

No trip to San Juan is complete without a stroll along the beautiful Princess Promenade, a carefully restored historic landmark, one of the most visited in the capital. Built in 1853, this esplanade skirts the curved city walls on the southern side of Old San Juan and is quite picture-perfect, with the San Juan Bay on the one side and the impressive fortification walls on the other.

The Promenade is equally suited for both walking and people-watching. It is also a great place to visit for families with children – easily accessible and traffic-free. The abundance of trees here provides plenty of shade, and there are lots of artisan stalls and street vendors selling local food. The area also often hosts festivals and fairs on weekends.

From here, you can make a slight detour to the narrow path, known as Paseo El Morro, leading to the historic El Morro Fort and the nearby San Juan Gate, which is the only city gate remaining from the colonial period.

Princess Promenade gets its name from an old 1837 building, located here, known as La Princesa. Originally, this building served as a municipal prison, although presently it houses the headquarters of the Puerto Rico Tourism Company and an art gallery.

Built in the late 1700s, the San Juan Gate is a giant (40 feet high) structure, the last remaining of the original five gates carved into the three-mile wall that once surrounded the city. Today, the wall wraps around Old San Juan, from the cruise ship piers on San Juan Harbor to the capitol on the Atlantic.

Originally, each gate had a designated function. The red gate of San Juan played a symbolic role, serving as the main entrance to the city, and was named in honor of Saint John the Baptist. The first thing you notice approaching it is the inscription of The Sanctus ("Holy") hymn from the Catholic liturgy.

The city wall is the most enduring symbol of Puerto Rico and was built by the Spanish between 1539 and 1782. Made of sandstone, rubble, and mortar blocks – 20 feet thick, the wall measures 45 feet wide and 40 feet high in some parts and was meant to protect San Juan from invaders, notably the English, the Dutch, and the Americans. Its iconic sentry boxes now symbolize the island's Spanish heritage and resilience in an ever-changing world.

Nearly impenetrable to foreign attack, the city wall proved defenseless, nonetheless, against modern automobile traffic, pollution, and misguided attempts to preserve it that have seriously endangered the wall, leaving it crumbling in some places.

Currently a National Historic Site, the city wall is maintained by the National Park Service which attempts to recreate the magic mixture of sand, water, and limestone that was once used to stucco the wall. Along with the adjoining fortresses of El Morro and San Cristóbal, the city wall attracts 1.2 million visitors each year.

Tip:
As you walk through the gate, just pause for a second and notice how thick the walls really are. Also, check out the street vendors outside, on the corner, offering refreshments including Puerto Ricans' favorite, piragua.

La Fortaleza, or the Fortress, is the current official residence of the Governor of Puerto Rico. Built between 1533 and 1540 to defend the harbor of San Juan, it is the oldest executive mansion in the New World. During the 1640 reconstruction, the chapel of Santa Catalina, then located outside the city walls, was demolished and integrated into the complex, which, upon that, assumed the new (current) name, Palacio de Santa Catalina.

La Fortaleza was the first defensive fortification built in San Juan, and the first of the series of military installations designed to protect the city, among which were the Fort San Felipe del Morro and Fort San Cristóbal. The construction was authorized by Charles V, the Holy Roman Emperor, as a defensive measure against the attacks from Carib Indians and the rivaling European powers.

The fortress underwent massive reconstruction in 1846 to convert from military use to a palatial residence. Since then, La Fortaleza has been the home to more than 170 governors of Puerto Rico and hosted various dignitaries, including President John F. Kennedy and his wife, Jacqueline Kennedy, who stayed here in 1961. At present, the complex consists of a few attached buildings with formal living quarters on the second floor, and private quarters on the third. The palace overlooks the high city walls fronting the bay, and its northern part contains sheltered gardens and a swimming pool.

The complex has been a UNESCO World Heritage Site since 1983 and as such may present definite interest to both history and architecture buffs with a taste for Spanish designs.

Arms Square is the de-facto central square of San Juan. Over the years, it has changed several names relative to the functions it served. Initially, in 1521, it was called Vegetables Square. Then, during the 17th-19th centuries, it was known as Arms Square, for being the grounds for military drills. After that, in the early 20th century, it turned back to being called Vegetables Square once again, serving as a marketplace, before it finally re-assumed the Arms Square title.

The plaza is modeled on the classic squares of Madrid and Mexico City. Although it factually existed for centuries, it was not until 1840 that the city council approved its proper development, which started in 1851. It was at that time that the four bronze statues, oil-coated to simulate marble, representing Commerce, Industry, Science, and the Arts, arrived here (there were a total of eight statues to be installed, but the other four were lost). In 1872, the original statues were replaced with the new marble ones, representing the Four Seasons, put in the four corners of the square.

In 1955, two circular fountains and two lampposts in the center were added. The four statues were then configured in a circular fountain outside the Palacio de la Real Intendencia, which is the seat of the Department of State of Puerto Rico, on the western side of the square.

A highlight of the northern side is the Casa Alcaldía – home of the San Juan City Hall. Built in 1789, this Spanish colonial-style edifice with twin turrets resembles its sister building in Madrid. The tinkling of the fountain, the comfortable seating in the shade of the trees, and the presence of several old-style coffee booths selling snacks have long attracted tourists as a good spot for a sightseeing break when you can stretch out your feet and soak up some of the everyday comings and goings.

The laid-back atmosphere of the place also made it a popular gathering venue with locals, offering a chance to buy kids some traditional treats (like sesame-seed lollipops or coconut candies), watch shows, play dominoes, or chit-chat with friends.

Proudly presiding over the bay of San Juan is the imposing La Fortaleza (Fortress), formally known as the Palace of Santa Catalina, the official residence of the Governor of Puerto Rico. The narrow road leading to the building, called Fortaleza Street, is the main artery of San Juan's historic quarter, cutting through most of it, and is also the oldest street in the area. It starts from Columbus Square and for the whole of its duration is lined with governmental buildings, hotels, perfumeries, craft shops, jewelry stores, and restaurants, gradually transforming into Avenue Juan Ponce de León in the east.

Just like many other colorful cobblestone streets in Old San Juan, each one more photogenic than the other, this thoroughfare is an important tourist attraction, in large part due to its historical and cultural significance. Visiting Fortaleza Street should be an integral part of every Old San Juan itinerary.

While the walled-in Old City has no shortage of vibrant photo spots, Fortaleza Street stands out above the rest due to the display of umbrellas – at the end of the street, near La Fortaleza itself – creating an overhead canopy that makes it particularly recognizable. These umbrellas tend to change colors during the year, from rainbow to all pink. Before the umbrellas, La Fortaleza Street was adorned with colorful kites.