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Nuclear stellar clusters(NSCs)are known to exist around massive black holes(MBHs)in galactic nuclei.The properties of these extremely dense clusters are strongly related to the MBH they host,and both are likely to co-evolve together.Moreover,NSCs contain several distinct stellar populations and among these groups of stars,the youngest ones often form disk-like structures.NSCs are thought to have formed through the infall of multiple globular clusters(GCs)and/or through in-situ star formation,following gas inflow to the nucleus of the galaxy.Here we will study the first scenario by means of fully self-consistent direct N-body simulations.In particular we will present models set up with data from the Milky Way bulge,Globular Cluster System and central MBH.We ran several high precision simulations,also including the possibility that the constituent clusters host intermediate mass black holes(IMBHs).Due to dynamical friction,the GCs decay one after the other toward the Galactic center,where they merge originating the NSC.This process leads to a final product which exhibits many of the observed features of the Milky Way NSC.We will discuss how this scenario produces observational signatures in the form of age segregation leading to efficient mass segregation in NSCs.We will show that the IMBHs,when included,inspiral to the core of the newly formed NSC and segregate there.Although the IMBHs scatter each other,none is ejected from the NSC.The IMBHs are excited to high eccentricities and their radial density profile develops a steep power-law cusp.The relaxation rate of the NSC accelerates due to the presence of IMBHs as massive-perturbers,and in contrast to the IMBH-free case,the NSC develops a cusp already in its early evolutionary stages.This,in turn,fills the loss-cone and boosts the tidal disruption rate of stars obtaining a constraint on the existence of IMBHs in NSCs.We will also examine the gravitational waves(GWs)emission events in this scenario.Finally we will present the dynamical evolution of young stellar disks in NSCs,both in presence and in absence of a central MBH.We will discuss the observational signatures of these structures and their impact on the properties of the central regions of galaxies.