Because I returned in 2009 I could see the "huge caravansary under restoration" in its restored state. I still could not visit the central building, because that is only opened during exhibitions, but guards let me take some shots in the courtyard.
This former caravansary is the Rüstem Paşa caravansery's, which is not usually open. It was built by Sinan around 1560 for the same man who built the wonderful mosque in Istanbul, he was grand vizier and son in law of sultan Süleyman. There are two inner courts, the complex has two floors. The smaller inner court was for camels and horses, the larger courtyard was for the travellers.