The eastern end of Bristol Cathedral is highly unusual for a number of reasons. Firstly, it was conceived as a "hall church", meaning that the aisles are the same height as the choir. While a feature of German Gothic architecture, this is rare in Britain, and Bristol cathedral is the most significant example. In the 19th century, G. E. Street designed the nave along the same lines. The effect of this elevation means that there are no clerestory windows to light the central space, as is usual in English Medieval churches. The north and south aisles employ a unique manner where the vaults rest on tie beam style bridges supported by pointed arches. All the internal light must come from the aisle windows which are accordingly very large. In the choir, the very large window of the Lady chapel is made to fill the entire upper part of the wall, so that it bathes the vault in daylight, particularly in the morning.