On 18 April 1867, the Ottoman government ordered the Ottoman garrison, which had been since 1826 the last representation of Ottoman suzerainty in Serbia, withdrawn from Kalemegdan. The forlorn Porte's only stipulation was that the Ottoman flag continue to fly over the fortress alongside the Serbian one. Serbia's "de facto" independence dates from this event. In the following years, urban planner Emilijan Josimović had a significant impact on Belgrade. He conceptualised a regulation plan for the city in 1867, in which he proposed the replacement of the town's crooked streets with a grid plan. Of great importance also was the construction of independent Serbian political and cultural institutions, as well as the city's now-plentiful parks. Pointing to Josimović's work, Serbian scholars have noted an important break with Ottoman traditions. However, Istanbul—the capital city of the state to which Belgrade and Serbia "de jure" still belonged—underwent similar changes.