  Submillimeter single-dish telescopes offer two key advantages compared to
interferometers: they can efficiently map larger portions of the sky and
recover larger spatial scales. Nonetheless, fluctuations in the atmosphere
limit the accurate retrieval of signals from astronomical sources. Therefore,
we introduce a user-friendly simulator named ${\tt maria}$ to optimize scanning
strategies and instrument designs to efficiently reduce atmospheric noise and
filtering effects. We further use this tool to produce synthetic time streams
and maps from hydrodynamical simulations, enabling a fair comparison between
theory and reality. ${\tt maria}$ has implemented a suite of telescope and
instrument designs intended to mimic current and future facilities. To generate
synthetic time-ordered data, each mock observatory scans through the atmosphere
in a configurable pattern over the celestial object. We generate evolving and
location-and-time-specific weather for each of the fiducial sites using a
combination of satellite and ground-based measurements. While ${\tt maria}$ is
a generic virtual telescope, this study specifically focuses on mimicking
broadband bolometers observing at 100 GHz. To validate our virtual telescope,
we compare the mock time streams with real MUSTANG-2 observations and find that
they are quantitatively similar by conducting a k-sample Anderson-Darling test
resulting in p<0.001. Subsequently, we image the time-ordered data to create
noise maps and mock observations of clusters of galaxies for both MUSTANG-2 and
an instrument concept for the 50m Atacama Large Aperture Submillimeter
Telescope (AtLAST). Furthermore, using ${\tt maria}$, we find that a 50m dish
provides the highest levels of correlation of atmospheric signals across
adjacent detectors compared to smaller apertures (e.g., 42-cm and 6-m survey
experiments), facilitating removal of atmospheric signal on large scales.
