A castle - bridge - and a postmark

Again a cover from Czech Republic- from the Prague world exhibition! 

The 27Kc stamp - The stamp issued on September 7, 2016 depicts one of the most famous view of the Prague Castle with the Charles Bridge in the foreground. The view is offered from the right bank of Moldau river a few hundreds meters southwardly from the Charles Bridge. The multicoloured stamp is part of a stamp series dedicated to World Heritage sites in the Czech Republic.

Prague Castle has been an important symbol of the Czech state for more than a thousand years. It was founded in the 9th century and became the seat of Czech rulers and later presidents ( since 1918). The castle, one of the largest complexes in the world, is made up of historical palaces, offices, church and fortification buildings, gardens and picturesque spots. It covers an area of 45 hectares. The panoramic view of Prague Castle is one of the most spectacular in the world.

Charles Bridge is a stone Gothic bridge that connects the Old Town and Lesser Town (Malá Strana). It was actually called the Stone Bridge (Kamenný most) during its first several centuries. Its construction was commissioned by Czech king and Holy Roman Emperor Charles IV and began in 1357. In charge of the construction was architect Petr Parléř whose other works include the  St.  Vitus Cathedral  at  the Prague Castle. It is said that egg yolks were mixed into the mortar to strengthen the construction of the bridge.

The stamp printed in Czechoslovakia (Ceska) shows illustration of blue anemone (sasanka) flower on white; beauty of flowers series; 4k blue violet purple green, circa 2010 - anemones are also called “ wind flowers “ . Anemoi in Greek means wind. 

The Postmarks : 

Occasional postmark with the text "PRAGA 2018 EXPO, Olympik Congress, Prague 8" for the occasion of the World Exhibition PRAGA 2018, the stamp picture is a stylishly modified postage stamp with text

An occasional postage stamp with the text "PRAGA 2018, World Exhibition of Postage Stamps, Prague 8" in the postmark is a stylistically modified globe, a globe outline and a postal envelope.

The other philatelic material on the cover is a commonerative sticker - probably APOST sticker . I have been unable to find details about it yet ! 

Thanks Alexander for the cover !