It’s always a blur when it arrives — five concerts over two weekends. This time was especially poignant because James Conlon was stepping down after 37 years. It wasn’t until I said goodbye in the Green Room that I realized I had been covering him here for 25 years. And Music Hall closed its doors for a massive rehab, which began early Sunday morning, literally hours after that final Hallelujah Chorus. Here is a photo gallery from last month.