Alphen aan den Rijn is a town in the municipality of Alphen aan den Rijn. A resident of Alphen aan den Rijn is called an Alphenaar. Alphen aan den Rijn is the capital of the homonymous municipality and is also the largest town in the municipality. Other cities in this  municipality are Aarlanderveen, Benthuizen, Boskoop, Hazerswoude-Dorp,  Hazerswoude-Rijndijk, Koudekerk aan den Rijn and Zwammerdam.

The area in Alphen aan den Rijn was inhabited 2,000 years ago. In Roman times, the Old Rhine was the main branch of the Rhine. The river continued to flood sand and clay off, creating a landscape of levees and bowls. Alphen this is still recognizable in the naming of the districts “high side” and “low side”, on the left or the right bank of the river.
At the place where now the center of Alphen aan den Rijn is stood in Roman times the castellum Albanianae. The Romans built then also the first bridge over the Old Rhine. From the reign of the Roman emperor Claudius I (41 -. 54 AD), there were stationed divisions of the Roman army. The northern boundary of the Roman Empire, namely lay along the current Oude Rijn, and here were also built several fortified camps by the Romans. As found in the nearby village Zwammerdam remains of the Roman castellum Nigrum Pullum, and remains of six Roman barges. Already in Roman times developed trade and industry, which Alphen aan den Rijn slowly grew into an important trading center in the region. Germanic attacks, however, there were in 240 AD. end.
After much wrangling and problems with flooding, especially in Utrecht and Leiden, the Old Rhine was dammed in 1122 at Wijk bij Duurstede. The branch which first as ‘Lek’ began became the mainstream of the river. Since then, the Old Rhine came not burst its banks. During and after the Middle Ages, Alphen was a ambachtsheerlijkheid called Alphen en Rietveld.
In the 17th century Alphen continued to flourish. It was a staging post for riders and trade by land and water. On sections along the Old Rhine is still to see the towpath along which barges were towed.
The current municipality of Alphen aan den Rijn was formed in 1918. When the smaller municipalities Alphen, Aarlanderveen, and Oudshoorn were pooled. In 1964 the church was extended with Zwammerdam.
The weapon of Alphen aan den Rijn was granted on 8 May 1918. It consists of a black eight-pointed star on a white coat. Above the shield is a golden crown. The shield is held by two golden lions. The weapon was originally from the family van Alphen, a branch of the family Van Kralingen. One of Dirk Cralingen (born before 1189) had property near Alphen and called himself Van Alphen afterwards.
The striking Alphense lift the Gouwe Luis on the Gouwe was built in the late thirties. Gouwe was widened to improve the maritime route between Amsterdam and Rotterdam. Similar bridges were built in Boskoop and Waddinxveen. In World War II, there are explosives placed near the bridge to inflate them if necessary, which turned out to be unnecessary. By lightning, however, still detonated one of the charges. In the seventies, the bridge again heavily damaged in a collision with a tow truck that was 1.5 meters high. Parallel to the lift (for the road) is a swing bridge for the train.
From 1950 the town began to grow strong. Large extensions on the north side of the village were built originally with horror as ’the flats’ were viewed by the ancient Egyptians Alphen. From the 1990s was also built a large residential area south of the railway, Church and Zanen. Alphen developed into commuter town, which, however, came more and more jobs within the limits.