Written up in both of our tourbooks, we came across 'T Kelderke after a long day of touring. We ate at the downstairs restaurant, and it was packed out from the moment we walked in until the moment we left. We were fortunate enough to get a table right away, but they don't take reservations, so be prepared to wait.
The restaurant itself is small and cozy, with low ceilings and little light. Service was universally outstanding, from the charming host to the perfectly timed serving of our courses. I ordered a rustic ham on bone with lentils - a perfect, hearty end to a long, cold day of touring. My wife's carbonnade was easily the best we had on the trip, and the pear dessert we shared was a sublime end to a nearly perfect meal.
It's open for lunch as well, so if you're by the Grand Place and want to enjoy a great Belgian meal, T' Kelderke will fit the bill. Enthusiastically recommended