It is on the second part of Sophian Road. When you enter that part, jump over the river and then go up a little bit past a man or boy. After that there will be another part of the river again. Jump iover it and then there will be a Carnivine (You can catch it if you want)Then there will be a large space where the monument is, but remember after you tap the monument there will be Pokemon pinchers so be prepared
GL and hope I helped!