a museum; religious services, however, resumed in 2000. Imperial tombs The cathedral houses the remains of almost all the Russian emperors and empresses from Peter the Great to Nicholas II and his family, who were finally laid to rest in July 1998. Of the post-Petrine rulers, only Peter II and Ivan VI are not buried here. Peter II is buried in the Cathedral of Michael the Archangel in the Moscow Kremlin; Ivan VI was executed and buried in the fortress of Shlisselburg or Kholmogory (alleged discovery at Kholmogory in 2010 currently under forensic investigation). On September 28, 2006, 78 years after her death, Maria Feodorovna, Empress of Russia, was reinterred in the Cathedral of St Peter and Paul. Wife of Tsar Alexander III, and mother of Nicholas II (the last Russian tsar), Maria Feodorovna died on 13 October 1928 in exile in her native Denmark and was buried in Roskilde Cathedral in Denmark. In 2005, the governments of Denmark and Russia agreed that the empress's remains should be returned to Saint Petersburg in accordance with her wish to be interred next to her husband. Bell tower The bell tower (with spire) is the dominant feature of this cathedral and the fortress. It serves several functions as part of the structure: It is an architectural symbol, an important part of its shape and of the Peter and Paul Fortress. It is a part of the imperial tomb - the tombs are on the ground floor. It is a lightning rod protecting the cathedral. It is a viewing platform upon which excursions meet each hour from 12:00 till 18:00. It houses a carillon upon which concerts are periodically performed. When renovators were cleaning the angel on the spire in 1997, they found a note in a bottle left in one of the folds of the angel's gown. In the note, renovators from 1953 apologized for what they felt was rushed and shoddy work (Soviet premier Nikita Khrushchev wanted the angel refurbished for the 250th anniversary of the city that year). It is said that the renovators in 1997 left another message for future generations, but the contents of that message have not been revealed. History of the carillon When Tsar Peter I of Russia visited the Netherlands in 1698 he heard the perfectly tuned Hemony carillons in Amsterdam and Leiden pealing all 24 hours of the day, every quarter of an hour