Part of defense system built in Palawan by the Recollects from the 1620s to 1738, the mysterious ruins of a bastioned fort were recently discovered (November 2004) on Linapacan Island at Barangay Caseladan, said to be the original site of the town of San Miguel. Another set of ruins were found near San Miguel. It is uncertain if this or the fortification at San Miguel is the one referred to by the 1738/39 Report of Valdes Tamon as “muralla de piedra de figura irregular” or the one described in 1754 by Delgado a fortaleza. There are marked discrepancies between the Valdes Tamon description and the actual remains at Caseladan. The Valdes Tamon report shows a natural fortification strengthened by walls and other built structures. The Caseladan fortification may have been built after the Valdes Tamon report or may been a remodelling of the fortification reported in 1738.
The history of San Miguel, the principal settlement of Linapacan is unclear. Did it transfer sites more than once? If it did then Caseladan maybe one of many sites for San Miguel.