Carroll symmetries were introduced many years ago by Levy-Leblond and Gupta as a possible contraction of the Lorentz symmetries in which effectively the speed of light is sent to zero. The name was inspired by the bizarre property that Carroll particles cannot move. After many years of silence Carroll symmetries have returned to the stage since they have been recognized as symmetries that do occur in several special situations such as the horizon of a black hole. In this presentation I will discuss some of the basic properties and mysteries of Carroll symmetries.

We show that in order to understand the higher-dimensional origin of all supersymmetric branes in (toroidally) compactified string theory one needs to extend the family of branes with an additional set of so-called ``generalized monopoles''. We will show what these monopoles are and how they lead to interesting ``wrapping rules'' for the branes in string theory.

I will show how to construct gauge-invariant and U-duality covariant expressions for Wess-Zumino terms corresponding to general Dp-branes in arbitrary D less than 10 dimensions. A distinguishing feature of these Wess-Zumino terms is that they contain twice as many scalars as the 10-D compactified dimensions, in line with doubled geometry. It turns out that For D less than 10 the charges of the higher-dimensional branes can all be expressed as products of the 0-brane charges, which include the D0-brane and the NS-NS 0-brane charges. I will show how the general expressions for these charges determine the non-trivial conjugacy class to which some of the higher-dimensional D-branes belong. Some implications and extensions of our work will be discussed.