  In this paper we study area-filling curves, i.e. continuous and injective
mappings defined on [0,1] whose graph has positive measure. Current literature
calls them ``Osgood curves", but their invention is due to H. Lebesgue.
Stromberg and Tseng constructed homogeneous area-filling curves and offered an
elegant example. We show that an appropriate variant of Knopp's construction
attains the same homogeneity result. In Section 4 we discuss briefly the
existence of an ``invasive" curve, i.e. a continuous and injective mapping from
the half-open interval [0,1[ to the unit square, whose image has measure 1. In
the last section we discuss several aspects of the Lance-Thomas curve,
connecting it with the other construction due to Stromberg and Tseng.
