The USS Constitution, aka "Old Ironsides" is heading for dry dock for a 3 year refurbishment. I posted about her on my last visit to Boston. The link is here.
I happened to visit Boston on her last refurbishment. You get a very different perspective of the ship. First of all, they have to find guys who have skills no longer in fashion. Very few people are around that have the skills to repair a wooden sailing vessel. In the museum, they had a display of all the good luck coins that had been placed under her masts in previous refurbishments. Another interesting fact is how they get the wood to repair her. They get donations of Live Oak stumps that they then use to make her new timbers.
Even though she may not be available for boarding, it is still worth a visit if you happen to be in Boston.