  Let $\mathcal{P}$ be the set of points of a finite-dimensional projective
space over a local field $F$, endowed with the topology $\tau$ naturally
induced from the canonical topology of $F$. Intuitively, continuous incidence
abelian group structures on $\mathcal{P}$ are abelian group structures on
$\mathcal{P}$ preserving both the topology $\tau$ and the incidence of lines
with points. We show that the real projective line is the only
finite-dimensional projective space over an Archimedean local field which
admits a continuous incidence abelian group structure. The latter is unique up
to isomorphism of topological groups. In contrast, in the non-Archimedean case
we construct continuous incidence abelian group structures in any dimension $n
\in \mathbb{N}$. We show that if $n>1$ and the characteristic of $F$ does not
divide $n+1$, then there are finitely many possibilities up to topological
isomorphism and, in any case, countably many.
