City North America
San Juan
San Juan is the capital of Puerto Rico. It has an old stone wall beside the sea.
San Juan is the capital of Puerto Rico, on the island's north coast in the Caribbean. Its old town keeps a stone city wall and old forts that UNESCO lists as World Heritage. The 2020 census counted 342,263 people in San Juan.
San Juan, capital of Puerto Rico on the north coast (Larousse), keeps fortifications built between the 16th and 20th centuries to protect the city and its bay (UNESCO World Heritage, 1983). Census 1 April 2020: 342,263 in San Juan municipio (City Population).
Photo: Roger W, CC BY-SA 2.0, via Wikimedia Commons
Discover San Juan
San Juan is the capital of Puerto Rico. Puerto Rico is an island in the Caribbean Sea.
An old stone wall runs along the sea in its old town.
San Juan is the capital of Puerto Rico, an island in the Caribbean. Larousse places it on the north coast and lists its buildings from the 1500s, its museums and its tourism.
UNESCO lists the old city wall and forts as World Heritage. The census of 1 April 2020 counted 342,263 people in San Juan.
Larousse: capital of Puerto Rico, on the north coast; 16th-century monuments, museums, tourism. UNESCO (property 266, inscribed 1983, criterion vi): La Fortaleza, the later forts of San Felipe del Morro, San Cristóbal and San Juan de la Cruz (El Cañuelo), and a large part of the original San Juan City Wall, including San Juan Gate, built between the 16th and 20th centuries to protect the city and the Bay of San Juan. City Population (from the census): San Juan municipio 342,263 on 1 April 2020.
- Island
- Puerto Rico (capital)
- People in San Juan municipio (census, 1 April 2020)
- 342,263
- Coast
- the north coast (Larousse)
- World Heritage
- La Fortaleza and San Juan National Historic Site, listed 1983 (UNESCO)
The wall above the harbor
In this photo, a tall stone wall stands by the water. Buildings and trees sit on the hill behind it.
This photo was taken from the harbor on 9 April 2012. The old city wall rises above the water's edge, with trees and buildings on the hill behind it. The photographer's caption names Casa Blanca at the left and the old city gate at the far right.
The caption also says the walls are about 13 meters high and 6 meters thick.
Commons: 'Old San Juan, Puerto Rico (Casa Blanca, Old City Gate, Cathedral)', by Roger W (Flickr), CC BY-SA 2.0, license confirmed by FlickreviewR 2; taken 9 April 2012, 11:28, camera point 18.4652° N, 66.1196° W (0.30 km W of the city's Wikidata point). The photographer's description: a small panorama taken as his ship entered the harbor; the walls are 42 feet (13 m) high and 20 feet (6 m) thick, a double sandstone wall filled with sand. Wikidata: San Juan Gate (Q66660890), 0.34 km SW of the city point.
- Photo
- Old San Juan from the harbor, 9 April 2012, by Roger W
- In the photo
- Casa Blanca at the left and the old city gate at the far right (the photographer's caption)
- San Juan Gate
- about 0.3 km southwest of the city's Wikidata point (Wikidata)
Walls and forts
Long ago, people built thick walls and forts to protect San Juan. Today visitors come to see them.
UNESCO says San Juan's forts and city wall were built over a long time, from the 1500s to the 1900s, to protect the city and its bay. The builders took European designs and changed them to fit a Caribbean port.
The oldest is La Fortaleza. Later came the forts of San Felipe del Morro, San Cristóbal and San Juan de la Cruz. In 1983 UNESCO added them to its World Heritage List.
UNESCO: La Fortaleza, with the later fortifications of Castillo San Felipe del Morro, Castillo San Cristóbal and San Juan de la Cruz (El Cañuelo), and a large portion of the original City Wall, were built between the 16th and 20th centuries to protect the city and the Bay of San Juan; they adapted European designs and techniques to the conditions of Caribbean port cities and reflect Italian Renaissance, Baroque and French Enlightenment designs. Inscribed in 1983 under criterion (vi). San Juan National Historic Site was established in 1949 (UNESCO).
- Built
- between the 16th and 20th centuries, to protect the city and the Bay of San Juan (UNESCO)
- Forts
- La Fortaleza, San Felipe del Morro, San Cristóbal and San Juan de la Cruz (UNESCO)
- World Heritage
- inscribed in 1983 (UNESCO)
A city on a bay
Ships sail into San Juan's bay. Many visitors come to the city.
Old San Juan stands beside the Bay of San Juan, the bay its forts were built to guard. Ships still sail in past the old walls: the photographer took this picture from a cruise ship as it entered the harbor.
Larousse lists tourism among the things San Juan is known for, along with its museums and its buildings from the 1500s.
UNESCO: the fortifications protected the city and the Bay of San Juan, a strategically significant yet difficult tropical site. Commons description: the photo is a small panorama taken 'as the cruise ship enters San Juan harbor'. Larousse: 16th-century monuments, museums, tourism. City Population's administrative table counts San Juan as a municipio (municipality), the unit used here for the city's population.
- Bay
- the Bay of San Juan, which the forts were built to protect (UNESCO)
- Ships
- the photo was taken as a cruise ship entered the harbor (the photographer's caption)
- Visitors
- tourism (Larousse)
Warm all year
San Juan is warm in every month. March has the least rain.
The World Meteorological Organization's averages for 1981 to 2010 show that San Juan is warm all year. Average highs go from 28.4 °C in January to 31.8 °C in August and September, and nights stay above 22 °C.
Rain falls in every month. March is the driest, with 49.5 millimeters, and November the wettest, with 161.3. The year adds up to about 1,431 millimeters.
WMO World Weather Information Service, San Juan (National Weather Service; station listed at 18.43° N, 66.00° W; period 1981–2010 as given in the data): mean daily maximum 28.4 °C (Jan) to 31.8 °C (Aug, Sep); mean daily minimum 22.2 °C (Jan, Feb) to 25.7 °C (Aug). Precipitation 49.5 mm (Mar) to 161.3 mm (Nov); sum of the months 1,431.4 mm. Mean rain days 12.2 (Mar) to 19.6 (Nov, Dec).
- Average daily highs (WMO, San Juan, 1981–2010)
- 28.4 °C (January) to 31.8 °C (August and September)
- Average daily lows (same table)
- 22.2 °C (January and February) to 25.7 °C (August)
- Rain in a year (twelve months added up)
- about 1,431 mm
A capital that is changing
Fewer people live in San Juan than before. It is still a big city.
San Juan's population has been getting smaller. Censuses counted 437,745 people in 1990, 434,374 in 2000, 395,475 in 2010 and 342,263 in 2020. An estimate for 1 July 2025 gave 329,737.
Even so, San Juan is still a large city, with museums, an old town and a bay that visitors come to see.
City Population (San Juan municipio; censuses on 1 April): 434,849 (1980), 437,745 (1990), 434,374 (2000), 395,475 (2010), 342,263 (2020); estimate 329,737 (1 July 2025). From 2000 to 2020 the count fell by 92,111, about 21%.
- Census 1990
- 437,745 people in San Juan municipio (City Population)
- Census 2020
- 342,263 (City Population)
- Estimate, 1 July 2025
- 329,737 (City Population)
San Juan on the map
Find the Caribbean Sea on the globe. San Juan is on the north side of Puerto Rico.
San Juan lies at about 18.4° north and 66.1° west, on the north coast of Puerto Rico, the island's capital.
Measured from the city's center point on Wikidata, San Juan Gate is about 0.3 kilometer southwest, and the photo was taken about 0.3 kilometer to the west.
San Juan's Wikidata point (Q41211) lies at 18.465° N, 66.117° W; the Natural Earth/sheet point (18.44° N, 66.13° W) is 3.14 km SSW of it. From the Wikidata point: San Juan Gate (Q66660890) 0.34 km SW; the photo's camera point 0.30 km W. Larousse: north coast.
- Latitude
- about 18.4° north
- Longitude
- about 66.1° west
- Coast
- Puerto Rico's north coast (Larousse)
Amazing facts
-
San Juan's old forts were built over hundreds of years!
UNESCO says San Juan's forts and city wall were built between the 16th and 20th centuries.
UNESCO: La Fortaleza, El Morro, San Cristóbal, El Cañuelo and the City Wall were built between the 16th and 20th centuries.
-
San Juan's old wall rises right above the water!
The photographer's caption says San Juan's walls are about 6 meters thick, made of two sandstone walls with sand between them.
Commons description: walls 42 ft (13 m) high and 20 ft (6 m) thick; a double sandstone wall filled with sand.
-
In San Juan, even January is warm!
In the World Meteorological Organization's averages, San Juan's coolest month, January, still has an average high of 28.4 °C.
WMO normals (1981–2010): lowest mean maximum 28.4 °C (January); lowest mean minimum 22.2 °C (January, February).
Words to know
- fortification
- walls, forts and other buildings made to protect a place
- city wall
- a strong wall built around a town
- bay
- a part of the sea that curves into the land
- World Heritage
- places UNESCO lists as important for all people to protect
- sandstone
- a rock made of grains of sand pressed together
- census
- an official count of all the people in a place
Discovery challenge
-
San Juan is the capital of which island?
San Juan is the capital of which Caribbean island?
San Juan, on the north coast, is the capital of which island?
- Puerto Rico
- Iceland
- Madagascar
Show the answer
Puerto Rico
Puerto Rico!
Puerto Rico.
Puerto Rico.
-
What did people build to protect old San Juan?
What did people build in San Juan to protect the city and its bay?
According to UNESCO, what was built in San Juan between the 16th and 20th centuries to protect the city and its bay?
- Forts and a city wall
- A canal
- A tall tower of glass
Show the answer
Forts and a city wall
Forts and a city wall!
Forts and a city wall.
Fortifications: La Fortaleza, three later forts and the City Wall.
-
In which year did San Juan's walls become World Heritage?
In which year did UNESCO add San Juan's forts and wall to the World Heritage List?
La Fortaleza and San Juan National Historic Site were inscribed in which year?
- 1983
- 1949
- 2012
Show the answer
1983
1983!
1983.
1983 (the national historic site dates from 1949).
-
Which month has the least rain in San Juan?
In the World Meteorological Organization's averages, which month is driest in San Juan?
WMO normals (1981–2010): in which month does San Juan get its least rain, 49.5 mm?
- March
- November
- August
Show the answer
March
March!
March, with 49.5 millimeters.
March (49.5 mm).
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For parents & teachers
What children will learn
- Locate San Juan on Puerto Rico's north coast in the Caribbean.
- Explain why port cities built walls and forts in the past.
- Read a climate table for a warm Caribbean city.
- Use census numbers to describe a city whose population is shrinking.
Recommended ages: 3 to 17 · About 15 minutes
Talk about it
- Why might a city build its strongest walls along the water?
- What can old walls and forts teach us about a city's past?
- What could cause a city to have fewer people over time?
Try at home or in class
- Wall model: build a wall of two rows of blocks with sand poured between them, and test how sturdy it is.
- Measure it: mark 13 meters on the ground with a tape measure to see how high the photographer's caption says San Juan's wall is.
- Rain bars: draw a bar chart of San Juan's monthly rain and find the driest and wettest months.
Key vocabulary: fortification, city wall, bay, World Heritage, sandstone, census
Where these facts come from
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Natural Earth vector data , Natural Earth (NACIS) (Public domain)
- San Juan , Encyclopédie Larousse
- La Fortaleza and San Juan National Historic Site in Puerto Rico , UNESCO World Heritage Centre
- Puerto Rico: Administrative Division (Municipalities) , City Population (Thomas Brinkhoff), from census results
- San Juan: climatological information (1981–2010) , World Meteorological Organization, World Weather Information Service
- File:Old San Juan, Puerto Rico (Casa Blanca, Old City Gate, Cathedral).jpg (Roger W) , Wikimedia Commons
- Wikimedia Commons , Wikimedia Foundation (Per file (public domain, CC0, CC BY or CC BY-SA); see each media record)
Checked, not yet human-reviewed. Last updated November 1, 2026. Spotted a mistake? Tell us.