The Oude Kerk (Old Church), nicknamed Oude Jan ("Old John"), is a Gothic Protestant church in the old city center of Delft, the Netherlands. Its most recognizable feature is a 75-meter-high brick tower that leans about two meters from the vertical.
The Oude Kerk was founded as St. Bartholomew's Church in the year 1246, on the site of previous churches dating back up to two centuries earlier. The layout followed that of a traditional basilica, with a nave flanked by two smaller aisles.
During its build the foundations weren't strong enough to support the building, and the church began to lean. As they continued to build the church they tried to compensate its lean on each layer of the tower, but it remains to this day that only the 4 turrets at the top are truly vertical.
The tower with its central spire and four corner turrets was added between 1325–50, and dominated the townscape for a century and a half until it was surpassed in height by the Nieuwe Kerk (New Church). It is possible that the course of the adjacent canal had to be shifted slightly to make room for the tower, leaving an unstable foundation that caused the tower to tilt.
The 800-year-old Oude Kerk ("old church") is Amsterdam’s oldest building and oldest parish church, founded ca. 1213 and consecrated in 1306 by the bishop of Utrecht with Saint Nicolas as its patron saint. After the Reformation in 1578 it became a Calvinist church, which it remains today. It stands in De Wallen, now Amsterdam's main red-light district. The square surrounding the church is the Oudekerksplein.
By around 1213, a wooden chapel had been erected at the location of today's Oude Kerk. Over time, this structure was replaced by a stone church that was consecrated in 1306.
The church has seen a number of renovations performed by 15 generations of Amsterdam citizens. The church stood for only a half-century before the first alterations were made; the aisles were lengthened and wrapped around the choir in a half circle to support the structure. Not long after the turn of the 15th century, north and south transepts were added to the church creating a cross formation. Work on these renovations was completed in 1460, though it is likely that progress was largely interrupted by the great fires that besieged the city in 1421 and 1452.