During the final phase of 1452–1520, the tower was erected, financed by pilgrims and later by its proprietor, the city. Designed to reach 600 Mechlinian feet or about 167 metres, higher than any church tower would ever attain (Ulm Minster has measured 161 metres since the 19th century), the very heavy St. Rumbold's tower was built on what had once been wetlands, though with foundations only three metres deep its site appears to have been well-chosen. After a few years, in 1454, its chief architect Andries I Keldermans constructed the Saint Livinus' Monster Tower (or "St.-Lievensmonstertoren" as it is called in Dutch) in Zierikzee (in the present-day Netherlands), where leaning or sagging of the tower (now 62 metres but designed for ca. 130) could wreck the church. This concern led to fully separate edifices, a solution also applied in Mechelen. At both places, in the early 16th century the upper part of the tower was abandoned, not for technical but for financial reasons. St-Rumbold's should have been topped by a 77-metre spire but only seven metres of this were built, hence the unusual shape. A deliberately weak connection closed the gap between tower and church upon finishing the construction.