Muslim leaders welcomed visitors to view the proposals for the scheme and ask question at the event at Dudley Central Mosque.
Planning permission for the new mosque in Hall Street which will have a 52 ft high curved roof and a 62 ft minaret was approved last year.
But Dudley Muslim Association remains locked in a legal battle with Dudley Council over the land earmarked for building.
A Court of Appeal hearing over the plans is awaiting a new date.
The open event was organised in the wake of the English Defence League protest last month.
Muslim leaders said they wanted people to be able to ask questions about the work of the mosque and also about the plans for the new site and Islam.
Dozens of residents attend on Saturday with many keen to look inside the mosque for the first time and witness prayers taking place.
Other quizzed leaders on Islam while others wanted more information on the application for the new mosque site.
Amjid Raza, from the mosque's management committee, said people wanted to know if other sites had been considered for the mosque.
They also asked how much of the new building would be available to the whole community, where the money is coming from to pay for the building work and what is the latest on the court case.
"It was obvious many people had questions, not just about the mosque but about Islam in general," Mr Raza said.
"These people had questions but simply did not know who to ask, or did not know whether the questions were offensive.
"So many people came along and were very active in asking questions because they wanted to learn. It was a very good day and we are hopeful that we will do it again."
Members were on hand to give tours of the current mosque, which is housed in the former St Edmund and St John school building off Castle Street. Food and drinks were also served.
Several high-profile guests also attended the event at the current mosque, including the Mayor of Dudley Councillor Margaret Aston and Dudley North MP Ian Austin.
"This is my former school so I know it quite well," Mr Austin said. "I like to think myself and the Mayor are attending this event in the same way we would attend any other faith event in the borough.
"It is fantastic to see so many people of all faiths coming together like this to have a proper discussion."
West Midlands Fire Service also made an appearance, handing out information to visitors.
Other guests included Reverend Andrew Wickens, who is chairman of Dudley Interfaith Network, and the Bishop of Dudley, The Right Reverend Graham Usher.
Nicky Smith, who teaches religious education at Straits Primary School, said she came along to discover more about the Islamic community in Dudley.
"I am a religious education teacher, so even though I did have my own questions about the development of the mosque, my main aim was to come along and make some new contacts," Mrs Smith said. "I had a few questions and they were all answered very well. I think the open day was a fantastic idea."
Outline planning permission for the mosque, along with a community training and enterprise centre was granted in July 2008. The plan approved last year was for the full proposal, which included details on appearance and layout.
The land is owned by the association, but the council won a High Court hearing to trigger a buy-back clause for the land.
If the council is successful the land will be transferred back into the council ownership.