I visited this WHS in November 2014. After visiting the Market Square I headed straight to St Mary's Cathedral. It's neatly hidden behind tall buildings and nothing too special from outside. The interior is completely restored and apart from some golden relics and a shrine there's really nothing left to see. The main highlights are the bronze doors, baptistry and pillar which were on loan for some time at the St Michael's Church. I would never even classify such a church as a world heritage site and in my opinion it wouldn't even classify as a top national heritage. Next, I visited St Michael's church and although I preferred the exterior from that of the Dom, still I wasn't impressed and I really thought that this must be one of Germany's least interesting WHS ... then I went inside the church and was awestruck upon seeing the old colourful wooden ceiling. It's almost too good to be true. It's truly world class and deserves to be on the WH list on its own. The fact that it's free to visit is incredible at this day and age (especially after a recent visit to the Naumburg Cathedral which costs from 6 to 8.50e and isn't a WHS yet!!!). If you have enough time, I'd recommend a visit to the Roemer-Pelizaeus Museum which is mostly dedicated to Ancient Egyptian and Ancient Peruvian art including the second largest collection of Chinese porcelain in Europe.