  A special class of metrics, called universal metrics, solve all gravity
theories defined by covariant field equations purely based on the metric
tensor. Since we currently lack the knowledge of what the full of
quantum-corrected field equations of gravity are at a given microscopic length
scale, these metrics are particularly important in understanding quantum fields
in curved backgrounds in a consistent way. But, finding explicit universal
metrics has been a hard problem as there does not seem to be a procedure for
it. In this work, we overcome this difficulty and give a construction of
universal metrics of d-dimensional spacetime from curves constrained to live in
a (d-1)-dimensional Minkowski spacetime or a Euclidean space.
