The additional download files for Patrons can be found in the following posts (specific to your tier) or from the Master Map Index or the Descent into Avernus Index posts.
This is my interpretation of Basilisk Gate in Baldur's Gate and the surrounding area based off various source material and imagery.
Basilisk Gate. Standing tall against Baldur's Gate's eastern wall, Basilisk Gate provides passageway to the Outer City and the road beyond...at least normally, until the Flaming Fist shut the gate to stop the flow of refugees in and Baldurian's out of the city.

Basilisk Gate - Descent into Avernus is unofficial Fan Content permitted under the Fan Content Policy. Not approved/endorsed by Wizards. Portions of the materials used are property of Wizards of the Coast. ©Wizards of the Coast LLC.