The AdS/CFT correspondence provides a framework which unifies gravity, gauge theory and geometry. Since its introduction, this remarkable correspondence has provided us many interesting and yet somewhat surprising results. In this thesis, we have explored three aspects of the correspondence: (i) Consistent truncations, (ii) Wrapping branes on spindles, and (iii) Mass deformations of $\mathcal{N} = 4$ SYM.

The first part of this thesis is concerned with consistent truncations associated with wrapped brane configurations.
We present constructions of consistent truncations of $D=11$ supergravity and Type IIA supergravity on a 6-dimensional manifold given by $S^4$ twisted over a Riemann surface, and they are associated with M5- and NS5-branes wrapping over Riemann surfaces respectively. The resulting theories are both $D=5$, $\mathcal{N}=4$ gauged supergravity theories coupled to three vector multiplets, but the precise details of the gauging of the two theories are different.

In the second part of the thesis, we present a novel construction of supersymmetric $AdS_3$ solutions in $D=11$ supergravity, which are associated with wrapping M5-branes over four-dimensional orbifolds. In one case, the orbifold is a spindle fibred over another spindle, while in the other, it is a spindle fibred over a Riemann surface. We show that the central charges of the corresponding $d=2$ SCFTs calculated from the supergravity solutions agree with field theory computations.

In the third part of the thesis, we study mass deformations of $\mathcal{N}=4$ SYM theory that are spatially modulated in one spatial direction and preserve some supersymmetry. We focus on generalisations of
$\mathcal{N}=1^*$ theories and show that it is possible to preserve $d=3$ conformal symmetry associated with a co-dimension one interface. Holographic solutions are constructed using $D=5$ gravitational theories which arise
from consistent truncations of $SO(6)$ gauged supergravity. For mass deformations that preserve $d=3$ superconformal symmetry, we construct a rich set of Janus solutions which are supported by spatially dependent mass sources on either side of the interface. Limiting case of these solutions gives rise to novel RG interface solutions with $\mathcal{N}=4$ SYM on one side of the interface and the Leigh-Strassler SCFT on the other. Another limiting case gives rise to S-fold solutions. Specifically, we construct new classes of $AdS_4\times S^1\times S^5$ solutions of Type IIB string theory which have non-trivial $SL(2, \mathbb{Z})$ monodromy along the $S^1$ direction.