  YBa$_2$Cu$_3$O$_{7-\delta}$ is a good candidate to systematically study
high-temperature superconductivity by nanoengineering using advanced epitaxy.
An essential prerequisite for these studies are coherently strained
YBa$_2$Cu$_3$O$_{7-\delta}$ thin films, which we present here using NdGaO$_3$
(110) as a substrate. The films are coherent up to at least 100 nm thickness
and have a critical temperature of 89$\pm$1 K. The $a$ and $b$ lattice
parameters of the YBa$_2$Cu$_3$O$_{7-\delta}$ are matched to the in-plane
lattice parameters of NdGaO$_3$ (110), resulting in a large reduction of the
orthorhombicity of the YBa$_2$Cu$_3$O$_{7-\delta}$. These results imply that a
large amount of structural disorder in the chain layers of
YBa$_2$Cu$_3$O$_{7-\delta}$ is not detrimental to superconductivity.
