Construction on Fort Amsterdam was begun in 1625 by Dutch West India Company surveyor and engineer Crijn Fredericksz. Despite professional advice that a masonry structure would best withstand the elements of the waterfront site on which it was built, plus the depredations of rooting hogs and pigs, the fort was constructed of timber and suffered much degradation over time. A four-sided structure with bastions at each corner to protect the sod-covered rubble-filled walls of clay and sand, it was finally torn down in 1790 following the American Revolution. During its day, it was variously the center of New Amsterdam’s trading activity, soldiers’ barracks, by 1642 the Reformed Dutch Church, the WIC Director’s house, and a storage depot for West India Company goods.
Jaap Jacob's book https://www.newhollandfoundation.nl/wp-content/uploads/2015/11/PDF-Dutch-Colonial-Fortifications-in-North-America.pdf has extensive research on the many years in which changes and improvements to the Fort were made. See pages 12-14. He notes:
"An anonymous English description of New Amsterdam indicates that the building works were completed in 1661: … and a Fort foursquare, 100 yards on each side, at each corner flanked out 26 yards. In the midst of the East and westside is a gate opposite to the other; the walls are built with lime and stone, and within filled up with Earth to a considerable breadth for planting guns, whereon are mounted 16. guns. In this Fort is the Church, the Governors house, and houses for soldiers, ammunition, etc.38