This extravagantly decorated clandestine church built centuries ago when Catholicism was considered a crime is hidden in plain sight behind an unassuming front door in the city centre. Those walking down Juffrouw Idastraat would never imagine that within one of the typical terraced houses lies the enormous Parish of Saints James and Augustine where Catholics used to practice their faith in secret. Nobody is quite sure who built the church, but the stunning baroque plastering seems to suggest that it was the famous architect and artist Daniel Marot or one of his students. Book a free tour which takes you through the church and the attic to the more recent Bishop’s Chamber which is full of some of the original features and furniture that were used in the 1700s.

Tucked beneath Cologne’s City Hall, this underground site gives you a glimpse of the city’s Roman past. You can walk through the remains of the governor’s palace and parts of the old sewer system—surprisingly intact.

This museum is renowned for its rare collection of funerary artefacts representing the diffusion of cultures throughout the Lingnan region during the Han dynasty. One of the highlights is the tomb of King Zhao Mo dating back about 2,000 years, and other exhibits include gold, jade and other trinkets from the same period.

Cologne’s main opera house stages a mix of classic and contemporary productions, from Mozart to modern composers. The resident company is strong, and visiting performers keep the programme varied. The building itself is modern and a bit divisive—some love it, some don’t—but the acoustics are excellent.