diff --git a/.github/workflows/deploy-docker-images.yml b/.github/workflows/deploy-docker-images.yml
index 6cde84c1..6a811444 100644
--- a/.github/workflows/deploy-docker-images.yml
+++ b/.github/workflows/deploy-docker-images.yml
@@ -63,6 +63,7 @@ jobs:
         # prettier-ignore
         run: >
           make ${{ env.images }}
+          CAPELLA_DOWNLOAD_URL="https://mirror.umd.edu/eclipse/capella/core/products/releases/{}"
           CAPELLA_VERSIONS="${{ matrix.capella_version }}"
           DOCKER_PREFIX="${{ env.registry }}"
           CAPELLA_DOCKERIMAGES_REVISION="${{ steps.tag.outputs.branch }}"
diff --git a/Makefile b/Makefile
index b8b73010..0620a007 100644
--- a/Makefile
+++ b/Makefile
@@ -4,6 +4,9 @@
 # Add prefix to all dockerimage names, e.g. capella-collab
 export DOCKER_PREFIX ?=
 
+# URL used by to download Capella from
+CAPELLA_DOWNLOAD_URL ?=
+
 # T4C license secret (usually a long numeric string)
 T4C_LICENCE_SECRET ?= XXX
 
@@ -193,6 +196,7 @@ capella/base: base
 		--build-arg BUILD_ARCHITECTURE=$(BUILD_ARCHITECTURE) \
 		--build-arg BASE_IMAGE=$(DOCKER_PREFIX)$<:$(CAPELLA_DOCKERIMAGES_REVISION) \
 		--build-arg BUILD_TYPE=$(CAPELLA_BUILD_TYPE) \
+		--build-arg CAPELLA_DOWNLOAD_URL=$(CAPELLA_DOWNLOAD_URL) \
 		--build-arg CAPELLA_VERSION=$$CAPELLA_VERSION \
 		--build-arg "CAPELLA_DROPINS=$(CAPELLA_DROPINS)" \
 		--build-arg "INJECT_PACKAGES=$(INJECT_LIBS_CAPELLA)" \
diff --git a/capella/Dockerfile b/capella/Dockerfile
index b3945406..8c05ee85 100644
--- a/capella/Dockerfile
+++ b/capella/Dockerfile
@@ -61,6 +61,7 @@ FROM base_new as build_online
 # https://github.com/moby/moby/issues/26533#issuecomment-246966836
 ONBUILD ARG CAPELLA_VERSION="5.2.0"
 ONBUILD ARG BUILD_ARCHITECTURE="amd64"
+ONBUILD ARG CAPELLA_DOWNLOAD_URL
 ONBUILD COPY ./download_archive.py /opt/.download_archive.py
 ONBUILD RUN pip install --no-cache-dir requests && \
     python .download_archive.py ${CAPELLA_VERSION};
diff --git a/capella/download_archive.py b/capella/download_archive.py
index 03bf7b7c..d799773f 100644
--- a/capella/download_archive.py
+++ b/capella/download_archive.py
@@ -7,6 +7,7 @@
 
 https://download.eclipse.org/capella/core/products/stable/.
 """
+
 import os
 import pathlib
 import sys
@@ -17,7 +18,7 @@
 CAPELLA_INDEX_URL = (
     "https://mirror.dkm.cz/eclipse/capella/core/products/releases/"
 )
-CAPELLA_DOWNLOAD_URL = "https://www.eclipse.org/downloads/download.php?file=/capella/core/products/releases/{}&r=1"
+CAPELLA_DEFAULT_DOWNLOAD_URL = "https://www.eclipse.org/downloads/download.php?file=/capella/core/products/releases/{}&r=1"
 
 
 def get_directory_structure(url: str) -> list[str]:
@@ -51,9 +52,10 @@ def main() -> None:
         for arch in dir_content
         if arch.endswith("linux-gtk-x86_64.tar.gz")
     )
-    download_url = CAPELLA_DOWNLOAD_URL.format(
-        f"{capella_archive_path}{archive_name}"
-    )
+    download_url = os.getenv(
+        "CAPELLA_DOWNLOAD_URL", CAPELLA_DEFAULT_DOWNLOAD_URL
+    ).format(f"{capella_archive_path}{archive_name}")
+    print(f"Downloading Capella from `{download_url}`...")
 
     download_response = requests.get(download_url, timeout=120)
     download_response.raise_for_status()
diff --git a/docs/docs/capella/base.md b/docs/docs/capella/base.md
index 2fdc9d58..4a3a6904 100644
--- a/docs/docs/capella/base.md
+++ b/docs/docs/capella/base.md
@@ -110,16 +110,6 @@ If you want to install dropins manually, you can place the dropins in the
 copied into the `dropins` directory of the Capella client without any further
 processing.
 
-#### Optional: Customisation of the Capella client
-
-If you want to customize the Capella client even further, you can:
-
-1. extract the downloaded archive,
-1. apply any modifications (e.g., installation of plugins and/ or dropins) to
-   it, and
-1. compress the modified folder `capella` to get a `capella.zip` or
-   `capella.tar.gz` again.
-
 #### Optional: Workaround of pinned library versions to remove incompatibilities
 
 **Note:** _This workaround is normally handled in the Dockerfile and it is only
@@ -147,20 +137,44 @@ For more information refer to
 
 ### Build it manually with Docker
 
+#### Automatic download of Capella
+
 If you want to download the Capella archive automatically, use the following
-command. Does only work for
+command. It does only work for
 [supported Capella versions](introduction.md#supported-versions).
 
 ```zsh
 docker build -t capella/base capella --build-arg BUILD_TYPE=online --build-arg CAPELLA_VERSION=$CAPELLA_VERSION
 ```
 
+You can further customize the mirror to download the Capella archive from. If
+you don't want to use the default mirror, choose another mirror from
+[this list](https://www.eclipse.org/downloads/download.php?file=/capella/core/products/releases&format=xml).
+
+Then, append `/{}` to the mirror URL and pass it as a build argument to the
+above command, e.g.:
+
+```zsh
+--build-arg CAPELLA_DOWNLOAD_URL="https://mirror.umd.edu/eclipse/capella/core/products/releases/{}"`
+```
+
+#### Build with pre-downloaded version of Capella
+
 If you've downloaded the Capella archive manually before, use this command:
 
 ```zsh
 docker build -t capella/base capella --build-arg CAPELLA_VERSION=$CAPELLA_VERSION
 ```
 
+With this method, you can customize the Capella client before running the above
+command:
+
+1. Extract the downloaded archive,
+1. Apply any modifications (e.g., installation of plugins and/ or dropins) to
+   it, and
+1. Compress the modified folder `capella` to get a `capella.zip` or
+   `capella.tar.gz` again.
+
 ### Miscellaneous
 
 #### Download older debian packages manually