No, I did not see bikes there to rent

I would walk the Corniche. It is beautiful and there are coffee shops along the way where you can take a break while enjoying the view. You might also enjoy the market place. There are restaurants there or food stands. I imagine you would be able to fit both into your layover. I didn’t visit the museums but hear they are really interesting.

Not sure where al Al Katara is but the airport is a 20 minute ride into town hope this helps

Eu tive 1 dia inteiro em Doha e foi o suficiente. Eu contratei uma guia brasileira que mora lá. Uma fofa. Pessoa maravilhosa. Foi nos buscar no hotel com seu carro e levou em todos os lugares indicados. O nome dela e Lucimara e da pra falar com ela pelo Instagram com o nome @guiadoha. Super recomendo. Faria tudo exatamente igual.

Not far and it's a lovely walk; or get a quick taxi if it's blistering hot.

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You can find, male and female cloths/ garments, handcrafts, antiques and jewelries. Hope you enjoy shopping there