Drawing a geodetic polygon

import matplotlib.pyplot as plt
import matplotlib.patches as mpatches

import cartopy.crs as ccrs

desired_projections = [ccrs.PlateCarree(),
                       ccrs.RotatedPole(pole_latitude=45, pole_longitude=180)]
for plot_num, desired_proj in enumerate(desired_projections):

    ax = plt.subplot(2, 1, plot_num + 1, projection=desired_proj)

    ax.set_global()

    ax.add_patch(mpatches.Rectangle(xy=[-70, -45], width=90, height=90,
                                    facecolor='blue',
                                    alpha=0.2,
                                    transform=ccrs.PlateCarree())
                 )

    ax.add_patch(mpatches.Rectangle(xy=[70, -45], width=90, height=90,
                                    facecolor='red',
                                    alpha=0.2,
                                    transform=ccrs.Geodetic())
                 )

    ax.gridlines()
    ax.coastlines()

plt.show()

(Source code, png)