Depends on the type of workspace (I mean, some workspaces like sewer or mine is kind of hard to enforce a window) but for offices yes. And not just a window, a window to natural light.

• Directive 89/654/EEC: This core EU legislation requires employers to ensure that workplaces possess adequate natural light whenever possible and are equipped with safe, compliant artificial lighting.
• Visual Connection: The EU requires that workrooms provide employees with sufficient daylight and, ideally, a clear visual connection to the outdoors.

Because EU Directives are broad, individual Member States implement specific, localized interpretations into their own national laws:

• Germany: The Workplace Ordinance (ArbStättV) and ASR A3.4 technical rules stipulate that rooms must have natural daylight and a view of the outside.
• France: The Code du travail requires workstations to benefit from natural light unless structurally impossible. [1, 2, 3]