Maximilian Antiqua is a set of open Roman caps that accompanied Rudolf Koch’s Fraktur typeface, Maximilian. It was released in 1914 by Gebr. Klingspor.
There are various digitizations, including versions by Keystrokes a.k.a. Fonts For Design (adding a solid cut), Dieter Steffmann (with ahistoric small caps) and CastleType (as Maximillian CT). Ambrose is a reworked Maximilian Antiqua by Alan Meeks for Letraset. The sample shown here uses Maximillian CT.