The town, which Simcoe named "York", rejecting the aboriginal name, was built within a large protected bay formed by the Toronto Islands, which – at the time – was a long sandy peninsula, which formed a large natural harbour, featuring a great wetland marsh – fed by the Don River – at the eastern end (long since filled in), with the only opening to the lake at the western end (it was only later, in 1858, that the "Eastern Gap", was punched through the peninsula by a storm, creating the true Island). This large natural harbour was defended with the construction of a garrison (later to be known as Fort York), guarding the entrance on what was then a high point on the water's edge, with a small river on the inland side (Garrison Creek). Rejecting Mann's town plan, Simcoe had another town plan set up. This was a more compact plan, a gridiron settlement of ten square blocks, closer to the eastern end of the harbour, entirely behind the peninsula, near what is now Parliament Street. The ten blocks are known today as the "Old Town" neighbourhood.