The production of very-high-$n$ ($n\ensuremath{\sim}300$--500) strontium Rydberg atoms is explored using a crossed-laser-atom-beam geometry. $n$${}^{1}{S}_{0}$ and $n$${}^{1}{D}_{2}$ states are created by two-photon excitation via the $5s5p$ ${}^{1}{P}_{1}$ intermediate state using radiation with wavelengths of $\ensuremath{\sim}$461 and $\ensuremath{\sim}$413 nm. Rydberg atom densities as high as $\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{5}$ cm${}^{\ensuremath{-}3}$ have been achieved, sufficient that Rydberg-Rydberg interactions can become important. The isotope shifts in the Rydberg series limits are determined by tuning the 461-nm light to preferentially excite the different strontium isotopes. Photoexcitation in the presence of an applied electric field is examined. The initially quadratic Stark shift of the $n$${}^{1}{P}_{1}$ and $n$${}^{1}{D}_{2}$ states becomes near-linear at higher fields and the possible use of $n{}^{1}{D}_{2}$ states to create strongly polarized, quasi-one-dimensional electronic states in strontium is discussed. The data are analyzed with the aid of a two-active-electron (TAE) approximation. The two-electron Hamiltonian, within which the Sr${}^{2+}$ core is represented by a semi-empirical potential, is numerically diagonalized allowing the calculation of the energies of high-$n$ Rydberg states and their photoexcitation probabilities.