Praise be to Allaah.

Your request should be for a mosque which would be subject to all the rulings of the mosque, where you can hold congregational prayers and it can be a centre for your da’wah activities. In this case it would not be permissible for any rituals of kufr to be held in this mosque, because Allaah says (interpretation of the meaning):

“And the mosques are for Allaah (Alone), so invoke not anyone along with Allaah”[al-Jinn 72:18].

The Prophet (peace and blessings of Allaah be upon him) forbade making announcements about lost property, or buying and selling, in the mosque. He (peace and blessings of Allaah be upon him) forbade praying towards graves, because he (peace and blessings of Allaah be upon him) said, “Allaah cursed the Jews and Christians who took the graves of their Prophets as places of worship.” 

But if they do not allow that, and instead allow a public place for you and others, then it is permissible to pray there, just as you can pray when the time for prayer comes and you are in a park, or on the road, or on a plane, or in an airport. But try to make sure that the place is free of objectionable things, especially if there are idols set up, or venerated images hung up. And keep away from these objectionable things as much as you can.