Cologne Cathedral (Kölner Dom)📍📍
The Gothic colossus that dominates every Cologne photo started in 1248 and finished in 1880. UNESCO-listed since 1996. The interior is free, stroller-accessible, and the south transept's 2007 Gerhard Richter window📍 is a kaleidoscope a toddler will gawk at. Skip the 533-step tower climb. Time your visit for off-Mass hours (Sundays 10:00 and 11:30 are busy). Open daily 06:00–20:00.