diff --git a/.changeset/perfect-coats-train.md b/.changeset/perfect-coats-train.md
new file mode 100644
index 0000000000..9357f51370
--- /dev/null
+++ b/.changeset/perfect-coats-train.md
@@ -0,0 +1,26 @@
+---
+'@backstage/plugin-catalog': patch
+---
+
+Adds a new `EntitySystemDiagramCard` component to visually map all elements in a system.
+
+To use this new component with the legacy composability pattern, you can add a new tab with the component on to the System Entity Page in your `packages/app/src/components/catalog/EntityPage.tsx` file.
+
+For example,
+
+```diff
+ const SystemEntityPage = ({ entity }: { entity: Entity }) => (
+   <EntityPageLayoutWrapper>
+     <EntityPageLayout.Content
+       path="/*"
+       title="Overview"
+       element={<SystemOverviewContent entity={entity} />}
+     />
++    <EntityPageLayout.Content
++      path="/diagram/*"
++      title="Diagram"
++      element={<EntitySystemDiagramCard />}
++    />
+   </EntityPageLayoutWrapper>
+ );
+```
diff --git a/packages/app/src/components/catalog/EntityPage.tsx b/packages/app/src/components/catalog/EntityPage.tsx
index 0f9cc98f4b..47bb9ef09f 100644
--- a/packages/app/src/components/catalog/EntityPage.tsx
+++ b/packages/app/src/components/catalog/EntityPage.tsx
@@ -39,6 +39,7 @@ import {
   EntityHasSystemsCard,
   EntityLinksCard,
   EntityPageLayout,
+  EntitySystemDiagramCard,
 } from '@backstage/plugin-catalog';
 import { EntityProvider, useEntity } from '@backstage/plugin-catalog-react';
 import {
@@ -501,6 +502,11 @@ const SystemEntityPage = ({ entity }: { entity: Entity }) => (
       title="Overview"
       element={<SystemOverviewContent entity={entity as SystemEntity} />}
     />
+    <EntityPageLayout.Content
+      path="/diagram/*"
+      title="Diagram"
+      element={<EntitySystemDiagramCard />}
+    />
   </EntityPageLayoutWrapper>
 );
 
diff --git a/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.test.tsx b/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.test.tsx
new file mode 100644
index 0000000000..baa8c667d2
--- /dev/null
+++ b/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.test.tsx
@@ -0,0 +1,124 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { ApiProvider, ApiRegistry } from '@backstage/core';
+import {
+  catalogApiRef,
+  CatalogApi,
+  EntityProvider,
+} from '@backstage/plugin-catalog-react';
+import { Entity, RELATION_PART_OF } from '@backstage/catalog-model';
+import { renderInTestApp } from '@backstage/test-utils';
+import React from 'react';
+import { SystemDiagramCard } from './SystemDiagramCard';
+
+describe('<SystemDiagramCard />', () => {
+  beforeAll(() => {
+    Object.defineProperty(window.SVGElement.prototype, 'getBBox', {
+      value: () => ({ width: 100, height: 100 }),
+      configurable: true,
+    });
+  });
+
+  afterEach(() => jest.resetAllMocks());
+
+  it('shows empty list if no relations', async () => {
+    const catalogApi: Partial<CatalogApi> = {
+      getEntities: () =>
+        Promise.resolve({
+          items: [] as Entity[],
+        }),
+    };
+
+    const entity: Entity = {
+      apiVersion: 'v1',
+      kind: 'System',
+      metadata: {
+        name: 'my-system2',
+        namespace: 'my-namespace2',
+      },
+      relations: [],
+    };
+
+    const { queryByText } = await renderInTestApp(
+      <ApiProvider apis={ApiRegistry.from([[catalogApiRef, catalogApi]])}>
+        <EntityProvider entity={entity}>
+          <SystemDiagramCard />
+        </EntityProvider>
+      </ApiProvider>,
+    );
+
+    expect(queryByText(/System Diagram/)).toBeInTheDocument();
+    expect(queryByText(/system:my-namespace2\/my-system2/)).toBeInTheDocument();
+    expect(
+      queryByText(/component:my-namespace\/my-entity/),
+    ).not.toBeInTheDocument();
+  });
+
+  it('shows related systems', async () => {
+    const catalogApi: Partial<CatalogApi> = {
+      getEntities: () =>
+        Promise.resolve({
+          items: [
+            {
+              apiVersion: 'backstage.io/v1alpha1',
+              kind: 'Component',
+              metadata: {
+                name: 'my-entity',
+                namespace: 'my-namespace',
+              },
+              spec: {
+                owner: 'not-tools@example.com',
+                type: 'service',
+                system: 'my-system',
+              },
+            },
+          ] as Entity[],
+        }),
+    };
+
+    const entity: Entity = {
+      apiVersion: 'v1',
+      kind: 'System',
+      metadata: {
+        name: 'my-system',
+        namespace: 'my-namespace',
+      },
+      relations: [
+        {
+          target: {
+            kind: 'Domain',
+            namespace: 'my-namespace',
+            name: 'my-domain',
+          },
+          type: RELATION_PART_OF,
+        },
+      ],
+    };
+
+    const { getByText } = await renderInTestApp(
+      <ApiProvider apis={ApiRegistry.from([[catalogApiRef, catalogApi]])}>
+        <EntityProvider entity={entity}>
+          <SystemDiagramCard />
+        </EntityProvider>
+      </ApiProvider>,
+    );
+
+    expect(getByText('System Diagram')).toBeInTheDocument();
+    expect(getByText('system:my-namespace/my-system')).toBeInTheDocument();
+    expect(getByText('component:my-namespace/my-entity')).toBeInTheDocument();
+  });
+});
diff --git a/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.tsx b/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.tsx
new file mode 100644
index 0000000000..df20e910aa
--- /dev/null
+++ b/plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.tsx
@@ -0,0 +1,162 @@
+/*
+ * Copyright 2021 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  Entity,
+  RELATION_PROVIDES_API,
+  RELATION_PART_OF,
+  serializeEntityRef,
+} from '@backstage/catalog-model';
+import {
+  catalogApiRef,
+  getEntityRelations,
+  useEntity,
+} from '@backstage/plugin-catalog-react';
+import {
+  DependencyGraph,
+  DependencyGraphTypes,
+  InfoCard,
+  Progress,
+  useApi,
+  ResponseErrorPanel,
+} from '@backstage/core';
+import { Box, Typography } from '@material-ui/core';
+import ZoomOutMap from '@material-ui/icons/ZoomOutMap';
+import React from 'react';
+import { useAsync } from 'react-use';
+
+function simplifiedEntityName(
+  ref:
+    | Entity
+    | {
+        kind?: string;
+        namespace?: string;
+        name: string;
+      },
+): string {
+  // Simplify the diagram output by hiding only the default namespace
+  return serializeEntityRef(ref)
+    .toString()
+    .toLocaleLowerCase('en-US')
+    .replace(':default/', ':');
+}
+
+/**
+ * Dynamically generates a diagram of a system, its assigned entities,
+ * and relationships of those entities.
+ */
+export function SystemDiagramCard() {
+  const { entity } = useEntity();
+  const currentSystemName = entity.metadata.name;
+  const currentSystemNode = simplifiedEntityName(entity);
+  const systemNodes = new Array<{ id: string }>();
+  const systemEdges = new Array<{ from: string; to: string; label: string }>();
+
+  const catalogApi = useApi(catalogApiRef);
+  const { loading, error, value: catalogResponse } = useAsync(() => {
+    return catalogApi.getEntities({
+      filter: {
+        kind: ['Component', 'API', 'Resource', 'System', 'Domain'],
+        'spec.system': currentSystemName,
+      },
+    });
+  }, [catalogApi, currentSystemName]);
+
+  // pick out the system itself
+  systemNodes.push({
+    id: currentSystemNode,
+  });
+
+  // check if the system has an assigned domain
+  // even if the domain object doesn't exist in the catalog, display it in the map
+  const catalogItemDomain = getEntityRelations(entity, RELATION_PART_OF, {
+    kind: 'domain',
+  });
+  catalogItemDomain.forEach(foundDomain =>
+    systemNodes.push({
+      id: simplifiedEntityName(foundDomain),
+    }),
+  );
+  catalogItemDomain.forEach(foundDomain =>
+    systemEdges.push({
+      from: currentSystemNode,
+      to: simplifiedEntityName(foundDomain),
+      label: 'part of',
+    }),
+  );
+
+  if (catalogResponse && catalogResponse.items) {
+    for (const catalogItem of catalogResponse.items) {
+      systemNodes.push({
+        id: simplifiedEntityName(catalogItem),
+      });
+
+      // Check relations of the entity assigned to this system to see
+      // if it relates to other entities.
+      // Note those relations may, or may not, be explicitly
+      // assigned to the system.
+      const catalogItemRelations_partOf = getEntityRelations(
+        catalogItem,
+        RELATION_PART_OF,
+      );
+      catalogItemRelations_partOf.forEach(foundRelation =>
+        systemEdges.push({
+          from: simplifiedEntityName(catalogItem),
+          to: simplifiedEntityName(foundRelation),
+          label: 'part of',
+        }),
+      );
+
+      const catalogItemRelations_providesApi = getEntityRelations(
+        catalogItem,
+        RELATION_PROVIDES_API,
+      );
+
+      catalogItemRelations_providesApi.forEach(foundRelation =>
+        systemEdges.push({
+          from: simplifiedEntityName(catalogItem),
+          to: simplifiedEntityName(foundRelation),
+          label: 'provides API',
+        }),
+      );
+    }
+  }
+
+  if (loading) {
+    return <Progress />;
+  } else if (error) {
+    return <ResponseErrorPanel error={error} />;
+  }
+
+  return (
+    <InfoCard title="System Diagram">
+      <DependencyGraph
+        nodes={systemNodes}
+        edges={systemEdges}
+        nodeMargin={10}
+        direction={DependencyGraphTypes.Direction.BOTTOM_TOP}
+      />
+      <Box m={1} />
+      <Typography
+        variant="caption"
+        style={{ display: 'block', textAlign: 'right' }}
+      >
+        <ZoomOutMap style={{ verticalAlign: 'bottom' }} /> Use pinch &amp; zoom
+        to move around the diagram.
+      </Typography>
+    </InfoCard>
+  );
+}
diff --git a/plugins/catalog/src/components/SystemDiagramCard/index.ts b/plugins/catalog/src/components/SystemDiagramCard/index.ts
new file mode 100644
index 0000000000..6d86b31b68
--- /dev/null
+++ b/plugins/catalog/src/components/SystemDiagramCard/index.ts
@@ -0,0 +1,17 @@
+/*
+ * Copyright 2021 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export { SystemDiagramCard } from './SystemDiagramCard';
diff --git a/plugins/catalog/src/index.ts b/plugins/catalog/src/index.ts
index 800c5c4693..7ab7b95dd7 100644
--- a/plugins/catalog/src/index.ts
+++ b/plugins/catalog/src/index.ts
@@ -29,4 +29,5 @@ export {
   EntityHasSubcomponentsCard,
   EntityHasSystemsCard,
   EntityLinksCard,
+  EntitySystemDiagramCard,
 } from './plugin';
diff --git a/plugins/catalog/src/plugin.ts b/plugins/catalog/src/plugin.ts
index 19dc778280..20c7a865db 100644
--- a/plugins/catalog/src/plugin.ts
+++ b/plugins/catalog/src/plugin.ts
@@ -114,3 +114,12 @@ export const EntityHasSubcomponentsCard = catalogPlugin.provide(
     },
   }),
 );
+
+export const EntitySystemDiagramCard = catalogPlugin.provide(
+  createComponentExtension({
+    component: {
+      lazy: () =>
+        import('./components/SystemDiagramCard').then(m => m.SystemDiagramCard),
+    },
+  }),
+);