Attraction should have opened at beginning of month
Castletown Commissioners say they are "deeply frustrated" by the continued closure of the major tourism draw in the town, Castle Rushen.
The medieval fortress was expected to be open for visitors at the start of May but remains closed.
Work is being done on the drawbridge, shop and what's termed "fully accessible interpretation to the ground floor". There is currently scaffolding on the battlements.
The contractors are known to be having difficulties while they wait for essential materials and cannot sign the building back to MNH until they complete the works.
It's understood that coach-loads of visitors have been diverted in the last few days to other locations, depriving local shop keepers of early season trade.

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