The name 'Amersfoort' (Pronunciation: [ä´mursfOrt] <) derives from 'foort' or 'voorde' (cf. English 'ford') and 'Amer' (i.e. the Eem river, or water in general).
The name "Amersfoort" was first mentioned in the year 1028, an offical of the German Emperor Koenraad II was describing the belongings of a convent and used the name "Amersfoirde" for a part of the arable, which was a wade through through the river Eem (also named Amer)
Thanks to it favourable location, both on the water router (over the Eem river to the Zuiderzee) and land route (from Utrecht Eastward and Northward) the agricultural settlement developed into a small town, which on june 12th 1259 was granted city rights by the Bishop of Utrecht.
The city had two centres: het Havik, first mentioned in 1390,(which could come from "bend in a river" or "habour area") and de Hof (the Court and first mentioned in 1462). Het Havik was the city's port and its business centre. De Hof, prior to the granting of city rights, was the location of the residence of the Bishop's representatives and the city church, the St. Joriskerk (the Church of St. George). In 1132 there is a chapel mentioned, which later would become the St. Joriskerk (1243 the built was started and in 1534 it would become the church that it is now).
The whole city was walled, orginally by an earthen wall, later by a stone wall. Some remains can still be seen. For instance, in the Langestraat (Lit.: the Longstreet) we find the remains of the Kamperbinnenpoort (The Innergate to Kampen, a city in the nothern part of Holland) and on the Muurhuizen (wallhouses) we see the remains of the Plompetoren, also know as the Dieventoren (lit: Thieves Tower, refering to the city jail located here [first mentioned as a prison in 1434] in the 19th century, last used in 1862).

Amersfoort is called 'Keistad' (lit.:Rocktown or Bouldercity), a name we 'earned' in the 17th century, not because we invented Rock&Roll as a dance, but because of a wager a crazy country squire ('Jonkheer') named Everard Meyster because he wanted to celibrate his new house.
He made a bet with some friends that he could talk the people of Amersfoort into dragging a large boulder, a stone that was deposited on Soester Moor by a glacier, weighting 9 tons, to the city. Four hundred Amersfoorters signed up for this feat. The boulder was pulled into the city over cannon balls. The squire won his wager and grandly spent the 3000 guilders on beer and salty pretzels. This all took place in 1661 but because other cities started to make fun of this event, the Amersfoorters burried the boulder in 1672 secretly in the hope the other cities would forget the event taken place. In 1903 we dug up the boulder again and gave it a prominent place in the city.
The inhabitants of the city are still called 'keientrekkers' (lit.: Boulder towers)