. The area around Alphen aan den Rijn has been inhabited for 2000 years. In the Roman era, the Oude Rijn was the main branch of the
Rhine River and formed the north border of the
Roman Empire. Since the rule of Emperor
Claudius (41–54 AD), divisions of the Roman army were stationed here. Consequently, several Roman fortifications were located along the Oude Rijn, including castellum
Albanianae in the centre of Alphen. The Romans had also built the first bridge over the Oude Rijn. Alphen was therefore an important commercial site in the area until Germanic raids ended that in 240 AD. After recurring problems with flooding, especially in Utrecht and Leiden, the Oude Rijn was dammed at
Wijk bij Duurstede in 1122, thereby making the
Lek River the main branch of the Rhine. The Oude Rijn has not flooded since. During the Middle Ages, Alphen was a
fiefdom called Alphen en Rietveld. over the Gouwe River was built in the 1930s. In the 17th century, Alphen became prominent again as a hub for commerce. The Oude Rijn was used for boat traffic; there are still portions along the river where the
towpath is present. The current municipality was formed in 1918 through the amalgamation of the smaller municipalities of
Alphen,
Aarlanderveen, and
Oudshoorn. In 1964, the municipality of Zwammerdam was added as well. In 2014 the municipalities of
Boskoop and
Rijnwoude were amalgamated as well, doubling the land area and increasing the population to over 100,000. During the Second World War, the majority of Jews from Alphen were deported and subsequently murdered; only a few survived. After the war, the Jewish congregation was disbanded and merged with the one in Leiden. A Jewish cemetery on the Aarkade was founded in 1802, but it was abandoned and razed in the 1960s, with the remains re-interred in
Katwijk; in 2012, after fifteen years of community activism by local historian Anke Bakker and
CDA council member
Alice Besseling, a monument was installed and the area turned into a city park. Since the 1950s, the city began to grow rapidly. A large new neighbourhood was built on the north side and Alphen became mostly a
commuter city. Other urban developments however did create local employment. Since the 1990s, a similar new development was built at the city's south side. |thumb|right|200px In recent years, a large part of the city centre has undergone a full urban renewal. Many buildings from the 1950s and earlier have been demolished to make place for modern architecture. This
"masterplan" included the addition of a new public square next to the riverbank, the construction of a performing arts theatre/
cinema, an upgrade of local
shops and the creation of
pedestrian streets. As of 2006, all of these projects on the left riverbank
Hoge Zijde have been finished and a new similar masterplan for the right riverbank
Lage Zijde has been developed and is being executed now. On 9 April 2011,
a gunman opened fire at a shopping centre in Alphen aan den Rijn, killing six people and subsequently taking his own life. On 3 August 2015, a newly built bridge flap of the under-renovation Juliana Bridge on the
Oude Rijn collapsed. It was being hoisted by two
cranes, different in size, floating on a
pontoon that was not stabilized. It became unbalanced shortly after the lifting started, fell and collapsed onto buildings. There were no injuries and fatalities, many inhabitants having already cleared the area. In total 51 properties were damaged. ==Demographics==