Kuala Lumpur Limestone is well known for its highly erratic karstic features. With the exception of the Batu Caves, exposures of Kuala Lumpur Limestone are found only in tin mines. Such exposures seldom exist nowadays after the closure of the tin mines. Ex-tin mined lands are covered with remnants of highly heterogeneous nature from slime to sand. Together with the underlying limestone karsts, they post great uncertainties and challenges for constructions. One of them is the triggering off of sinkholes. Amongst the various karstic forms, worth mentioning is the significant and sudden drop in limestone profile, in a range of 60m to more than 100m, within a building site, at places near to contact zones between limestone and other formations or fault zones.